It appears that the guy who was talking about DOOM4CE working in Windows CE 1.0 was wrong. There is a separate program, DoomCE, which only plays Episode 1 of DOOM that works on grayscale HPCs, and is available from
http://revolution.cx/DoomCE.htm
Maybe if I'm feeling lucky, I'll ask the guy who made DoomCE if I can take a peek at the source code and see if there's anything I'd be able to do.