Impossible and mod do not belong in the same sentence. A cherry switch simply closes a circuit. I have converted cap-active or rubber dome switches to mechanical before, and even some odd on/off switches and accelerometer switches( game controllers, but same circuit closing apparatus ) . I am mostly worried about key spacing and keeping the switch stuck to the PCB.
I am a programer who primarily uses emacs, and the happy hacking keyboard gives me a lot of vi(m) like control over keeping my fingers on my home keys. The only real major mod i feel like I might do is to add a track point pointer to it somewhere. I normally use a heavily moded kinesis advantage but this is more practical to drag around to different terminals. While I may buy a the Race board to bring to lan parties to show off to friends, its just not as practical as a HHK for my every-day needs.