I greatly appreciate the feedback provided thus far. Admittedly, one thing I hadn't thought about was the whistle and bell in the CC Berk, and presumably the horn in the CC F-3, not functioning after the conversion. Thanks for pointing this out. The work around described by Trainman9 is an option, but less than ideal. Honestly, I don't understand why Lionel didn'tengineer these locomotives to accept TMCC in a more straight foward fashion. My other option is to find a Berk from the Postwar Celebration Series which already has TMCC and Railsounds installed.
The method might still work if you have a Lionel PowerMaster. They are programmed as tracks and you can toggle back and forth using the sticky key approach.