Well, here's something on PowerPC Macs (No OSx86! ) to access the Firmware Command Prompt in Open Firmware.
Once you hear the startup chime, hit Cmd+Opt+O+F (OF for Open firmware, stating the obvious). You will get a white screen with black text.
I don't know any of the commands, maybe someone can help me with that, or I will post them later once I find them.
Oh -- I forgot. BE CAREFUL IN HERE!!! There are commands that are DANGEROUSLY close to internal system functions that computer noobs and Mac noobs shouldn't play with unless you read something in a manual that told you to use this.
--In Shorter Words...--
DON'T USE WITHOUT PRIOR OPERATING KNOWLEDGE!!!!