Here's a test build. In alt mode, the DISP button should now toggle MF (aka subject distance override). The left and right buttons should adjust focus, and up and down set focus to infinity and hyperfocal distance respectively. Overrides must be enabled for this to work.
I've never really used this (since the CHDK cams I've used have MF) and the code is a bit convoluted so I'm not totally clear on how this is supposed to work.