I just added an LCS WiFi module to my Legacy Base/Original Cab1 setup. I think the coolest part of the whole thing so far has been ditching the USB-Serial adapter hassle to get my Legacy base to talk to the Legacy System Utility. (Just to be clear for folks searching for this later, the Legacy System Utility does NOT run your trains via the LCS WiFi module. It's a "housekeeping" program - hence the Utility moniker - to update the firmware in the Legacy Base or the CAB2 remote, backup your Legacy base station's database - your locomotive roster information etc - restore the Legacy base station database and other Legacy base station software maintenance tasks.)
Since the V1 Legacy System Utility and the V2 update and presumably any future variants are Windows only, I thought I'd post my experience as a Mac user for others wondering if it's useable in a Mac universe.
It took a bit of configuration, but it's not overly complex and everything seems to be working just fine. My "universe" is all Mac, from my computer to my router.
I'm running Legacy System Utility (LSU) under Windows XP as for now I think it's the most common version of the Windows operating system for the intended audience. The update from V1 to V2 seems modest and I suspect the underlying core code was designed for XP. My Mac is a 2010 MacBook Pro but running the relatively recent OX X Yosemite (10.10.5). I will shortly take it to OS X El Capitan (10.11.x) and expect everything related to LSU will be fine. I use VMWare Fusion 7.1.2 to run Windows XP as a virtual machine inside my Mac operating system. VMWare's virtual network adapter for this XP "machine" is configured to use "Bridged Networking" set to "Autodetect" This configuration is done on the VMWare Mac program's menu under "Virtual Machine" menu then "Settings".
Once the LCS WiFi module was added to my Legacy base per the LCS WiFi instructions I added it to my local home network. I really wanted LCS to "just work" as part of my network (Join To Network switch setting on LCS WiFi module) rather than have it create it's own network (Access Point switch setting on LCS WiFi module) that I'd have to remember to select on my iPad/iPhone/MacBook-Windows XP Virtual Machine. It just seemed the most hassle free option. The only reason I might elect to set the LCS WiFi module up as it's own network would be if I have latency (delay) issues sending commands over WiFi. But my router is the most recent Airport Extreme base station and supports not only 2.4Ghz and 802.11a/b/g but also 5Ghz and 802.11n/ac. Most of my devices are connecting on the 5Ghz band using 802.11n/ac. The LCS WiFi is just 802.11b I believe so it's going to increasingly have the 2.4Ghz spectrum more to itself and I expect reducing congestion not rising congestion as more and more of my devices that are bandwidth hogs (Apple TV, laptops etc) connect on 802.11n/ac at 5GHz.
The "problem" is that unlike most routers Apple's Airport Extremes (and Time Capsules) don't directly support WPS setup via a convenient "WPS Button" on the outside of the router. And the LCS WiFi module has no way to enter network passwords to join a protected WiFi home network. But the Airport Extreme does allow WPS via software. I used the Airport Utility App on my MacBook (Airport Utility V6.3.5) and the WPS setting can only be accessed on the Airport Utility menu bar under "Base Station" and the option to "Add WPS Printer...." once you double click on your router and select "Edit". The LCS WiFi is not a printer but it doesn't matter. Once I selected "Add WPS Printer..." I chose the option to "allow WPS printer by" first attempt. (The PIN option is useless for the LCS WiFi since there is no interface on the LCS WiFi module to enter a PIN.) Then push the "WPS Enable" button for a few seconds on the LCS WiFi module. If you don't hold it down long enough it won't initiate a pairing. It may take a minute or so but you should get a notice in the Airport Utility App that "WPS printer successfully joined your network." The description will be "GainSpan WiFi Module" and you'll get a MAC Address. It's important to write the MAC address down paying attention to zero's vs Os. MAC here has nothing to do with Apple but the unique ID number in hexadecimal for the communication hardware inside the LCS module. The initial fast blink on the green LCS WiFi LED should go to slow blink at the point you get the successfully joining to the network.
At this point I was able to use both my iPhone (iPhone 6 and iOS 9.1) and iPad with the Lionel iCAB application ($50 in the iTunes App Store) to search for and connect to my LCS WiFi. The green LCS WiFi LED goes to steady green once the connection is made. Back on the Airport Utility App you'll want to connect to your Base Station (double click the airport image and select edit) and under the "Summary" tab look at the "Wireless Clients". Here you're looking for the MAC address you wrote down when the WPS joining completed. Double clicking the client or single clicking the triangle next to it should give you further detail, including the IP address assigned. Write down the IP address.
I disconnected from the LCS WiFi on my iOS device iCAB app. Then I went to my Windows XP virtual machine on my MacBook and started the Legacy System Utility V2 application. The communications window (also reachable under the menu bar option "Configure" and "Communications...") came up and I selected the method of "WiFi" and then entered the IP address I noted from the Airport Utility application and hit Enter. The bottom of the LSU application then showed my Base as connected.
I would note I initially had trouble with the LSU application finding my LCS WiFi module. I used the search function on the LSU communication window but after multiple search attempts it still failed to find my LCS WiFi module. During this period I saw the LCS WiFi module MAC address on the Airport Utility application but no IP address listed. I eventually tried repairing (WPS Enable above) after which point I couldn't even connect to the LCS WiFi module with the iOS iCAB app that had previously worked. I suspected a new IP address had been handed out and the old one was cached. So I deleted the iOS iCAB application completely (press on the app icon until it "wiggles" then press the "x" and confirm you want to delete) then performed the WPS Enable procedure and after successful I waited a few minutes then powered down my Legacy/LCS completely, rebooted my Airport router and once it was back up I repowered my Legacy/LCS equipment and waiting for a blinking green LED on the LCS WiFi to ensure it had reconnected with the router. At this point I was able to connect via the iOS iCAB app and find the IP address for the LCS WiFi module in Airport Utility and successfully connect via the LSU after disconnecting the iCAB application. I connected on the LSU application by manually entering the IP address. I never was able to get the LSU application to search and successfully find the LCS WiFi even though the iOS application was able to search successfully. Once everything was working I wanted to ensure any cached IP addresses - particularly on the Windows LSU application - continued to work so I created a DHCP reservation for the LCS WiFi module with it's current IP address to ensure it always got the same IP address everytime I turned it on. To set the reservation I went to the Airport Utility app, selected my Airport Extreme, clicked Edit then went to the Network tab. Under DHCP reservation I selected the "+" and then gave it a description (Lionel LCS WiFi) and chose to reserve by MAC address. Finally I entered the MAC address I first recorded when the WPS Printer add was successful and entered the current IP address for the LCS WiFi. This last part might be overkill.
Hopefully this proves helpful for someone else down the line.