I agree with the purchase of a TMCC command base. Would take 5 minutes to hook it up, is less expensive than a PS2 conversion, and then you could run the GP15 (and any other TMCC/Legacy locomotive) with your DCS remote. Another [more expensive] option is a Lionel Cab 1-L Base/Cab - would allow for additional features should you decide to get Legacy locos in the future.
I have the Trainman GP15 in MoPac colors - have not had it apart...yet. I plan to eventually rewire the motors to slow it down a bit and provide better low speed control.
I forgot to mention - if you get the TMCC Command Base, you will also want this MTH cable to connect the DCS TIU to the Command Base.