The PS32 board is a PS/3 board with a piggyback board that makes it appear like a PS/2 board. They come in 3V and 5V compatible models. If you have an existing PS/2 installation with a bad board, the installation of the PS32 board is the mechanical mounting, possibly lengthening a harness or two, and replacing the speaker with a 4 ohm model for 5V PS/2 replacement.
It's the same board that's in the PS/3 Steam Upgrade Kit. With the upgrade kit, you're just buying a bunch of harnesses and the like that you don't need. Unless your existing wiring is bad, it's just dropping in the replacement board and using the existing wiring.