Depending on how the trackball CP is mounted, might you want something a little more durable? I've come across quite a few PS/2 cables living in peoples homes where the pins was either mangled, pushed in or simply missing.
Why not use a
4-pin XLR connector? It's far more durable than a tiny PS/2 connector and gives your cab that durable look. Typically, I believe they price out at around $5 to $7 for each end. I've seen salvaged parts sell for as low as $2 or less each and an occasional eBay auction as low as $1 each. The panel mount female is ideal since they sometimes use
solder cups to connect the wire to. Which you can bolt into your cab.
I'm not aware of any specific high power applications that use the XLR, but with careful pin selection, inadvertantly plugging in the wrong equipment shouldn't do any damage.