According to this thread:
https://forums.ubisoft.com/showthread.php/1703696-Increasing-the-Chessmaster-s-Performance
It seems it is possible to use the Chessmaster GUI with other engines (i.e., other than The King). I am not that interested in using The King with other GUIs.
Yeah, I messed around with that before I transitioned to Linux. I experimented with running other engines (both Winboard and UCI) in the CM GUI and running The King engine in other GUIs (Arena). It's a lot of work; I'm not sure it's worth the effort, lol.
The good old days.