If this is one of the Mac clones that were allowed for a brief time before Steve Jobs came back to Apple and killed it off, then you can't assume there's a CMOS or anything like what's on a PC. Since Motorola was the one cranking out most of the PowerPC chips in those days, it makes sense they'd take a stab at building their own Mac clone, or even just a PPC based system.
Something that's traditionally been one of the best things about the Mac platform, be it PowerPC or even the new x86 systems, is that they're fairly legacy free. They aren't saddled with a 16-bit real-mode BIOS program or any of the other legacy garbage that has been holding back PC development for probably about the last 15 years or more.
I can't say as I know enough about the hardware of the really old Mac systems. There is likely a battery, but it would probably only be used for keeping the time. VERY rarely have I ever seen a situation where you need to get into the Mac equivalent of the BIOS/CMOS. I'm not even sure there was any sort of setup program on Macs before they started using OpenFirmware.
This actually sounds like the sort of question best taken to a newsgroup, where the odds of finding someone with knowledge of relatively obscure systems like this will be much higher. Of course I could just be completely wrong and it's not a PowerPC (processor) based system. And if that's the case, just ignore me and everything I just said. Haven't had my morning coffee yet.