How to add a second PS/2 keyboard to a PC that already has one?

How to add a second PS/2 keyboard to a PC that already has one?

My father has a Compaq 700Mhz slim PC running Windows XP. This has the two standard PS/2 ports, with a (French) keyboard and a mouse attached to them. For his studying he needs a Russian keyboard which I have finally been able to find (HP model I would say circa 2002 from the design), but this hooks up to PS/2.