Basically you have to swap 2 eproms on the main pcb, and then add a daughter card that connects to the main pcb via a ribbon cable. It's pretty straight forward. There are a few things you have to remove when plugging the ribbon cable in, but it's not bad.
Basically it's just the addition of a daughter card and change of character roms. Wait for a response from Riptor. He has (in your best terminator voice) "detailed files".
Like they said, its very simple. Remove the Z80 from the main board. A ribbon cable plugs in where the Z80 was on the main board. The other end of the ribbon connects to the daughterboard. Then you remove 5E & 5F eproms and install mspac eproms in their place.
Pac to pac plus is the same procedure except the two color proms need to be changed also 4A, 7F.
good deal, thanks guys. i could not t find a ms.pacman in my araea for under 600, but i picked up a fully working pacman for 125, but since i dont need two pacman's thought i would convert one to ms pac.
Bob Roberts has you covered on the 2 ROMS failry cheap. I just bought them myself not too long ago. I have a spare daughterboard and ribbon cable for $30 shipped if you need one.