You'll need at the very least a cable with a PS/2 or AT connector.
Does the cable detach from the keyboard using an
SDL connector? If so, you can replace it with a PS/2 cable easily enough, and Unicomp sells
SDL to PS/2 cables for $15.
Otherwise, you may have to open it up and do some soldering to attach an existing PS/2 cable to it. I don't have a pinout handy.
All of this is also assuming that it uses the Extended Set 2 protocol, and not the Set 3 protocol. If it uses Set 3, your best bet is instead
Soarer's adapter and to use USB.