From Thomas Richter's MMU.guide:
"The well known accelerators "MK-I" and "MK-II" are, compatible, but some members of the "Blizzard"-family, especially those equipped with a PPC processor are not. I've no overview about the P5 product family, though, and you might be on your own to check this out."
and
"Please remember, I do not own a P5 board, I've no documentation about their hardware whatsoever. In case something goes wrong, you possibly have to fine-tune the ENVARC:MMU-Configuration file to adapt or optimize it for your needs."
These two quotes are the reasons I've been reluctant to give it a shot. Tempted, yes. Gung-Ho no. :-D