Keyboard Mapping Software?

I just got a Gyration compact wireless keyboard, which I really like for its small size - reminds me of the original Mac keyboards, except fancier and wireless! Anyway, Gyration only does software for Windoze machines to accompany it. The regular keyboard keys (and mouse, for that matter) work just fine with OS 8 and above, but the "extra" keys are unmapped on a Mac. USB Overdrive will map mice and joysticks. Is there an equivalent product out there for pre-OS X operating systems which will map keyboards in OS 8 or 9? (OS X has keyboard mapping built-in, apparently, so it is not a problem when running in OS X.)