I think those at psu's should work... you'll need the pinout of course... http://home.earthlink.net/~supermac_insider/support/psconversion.html
and you'll also need the neo-pinout to know what to do with the at pinout... http://homearcade.org/BBBB/mvsjam.html .
I'd do the seccond link personally... not sure if the mvs would run off 110w...
The buttons should also work fine... basically any button with two prongs should work.
you know... if the at psu doesn't work (not enough power) You can modify an atx psu to not need a switch... http://timberland.10.forumer.com/viewtopic.php?t=57&postdays=0&postorder=asc&start=15
I posted a pic of my modded atx psu (I did it to run my naomi system, but it would be the same procedure in your case) if you need me to instruct you... just ask... I'll be happy to help how I can...