simple answer...
hardwire it to the power supply in the computer.
use the 5v and ground pins from the power supply, it will be switched on and off just like the ps/2 port, plus it will leave the ps/2 open for whatever you want to put on there.
the data isnt going through the ps/2, all you need is the power.
well.. thats my idea. if you dont want to cut the cord, pick up a ps/2 cable at the store, cut the end and use the wire to tap the power supply, and thne you have the right kind of connection on the other end.
~Mike