As far as I know the PS/2 hardware normally is not hotpluggable, and the
mainboard /can/ be damaged if you do it anyway. Are you sure it works
on your hardware without damaging it?
Although PS/2 is not technically designed for hot plug, i've found very
few pieces of modern hardware that don't successfully hot-plug
keyboards. I find if i boot with the keyboard (or KVM) attached, i can
pull it in and out pretty much at will. I often do this with my servers
at home. Of course, this has the potential to blow the board, so i'm
taking a risk every time i do it, but i haven't been bitten yet.