Well that sucks.
Go on a mac forum and ask them about it. Tell them what you want to do and what you have.
Hopefully someone there can tell you.
Here is what I could find.
http://www.lesswaiting.com/info100.html
"ADB: Older Macintosh and other Apple computer systems have ADB (Apple Desktop Bus) ports, which look similar to PS/2 ports. ADB accessories are usually less expensive than USB or wireless models. According to wikipedia.org, pre-1998 Macintosh systems and the Apple IIgs have ADB ports..... When connecting an ADB keyboard and mouse to some Apple Macintosh computer models, you may be surprised to find that there is no 2nd ADB port for the mouse, especially if you are more familiar with IBM/PC-compatible computer systems. This is because there is a port on the bottom or side of the keyboard for connecting the mouse to. It is actually possible to connect two ADB keyboards to a Macintosh computer at the same time, by plugging the 2nd keyboard into the first keyboard's mouse port (then the mouse can connect to the 2nd keyboard if desired)."
Does your keyboard have a socket in it for connecting a mouse? Perhaps you could buy an ADB keyboard that does.