The Ford rollers you are thinking of, Tom, are roller tip ROCKERS, not LIFTERS.
Ahh, that's it! I saved that posting, but it's buried in my notebook. Thanks for refreshing my memory.
All you need to use boost with the MegaSquirt is the correct MAP sensor. They come in 1, 2, and 3 BARs (1 is atmospheric pressure, then double, triple). The MS uses a MAP that mounts to the board. I'm assuming that type is available in 2 and 3 BAR versions like the standard GM MAP. I suppose you could alter the design to use a short pigtail to mount a GM style MAP if necessary.