Getting around Firmware Password?

You may want to check but he could be breaking a law by locking a system that doesn't belong to him. If so you could press charges and have him arrested. That would almost certainly change his tune.

 

From what I've read, you can change the physical amount of memory inside the computer by removing or adding memory DIMMs. Then zap the PRAM repeatedly to remove an Open Firmware password.
Never had occasion to test this information myself, but hopefully this works out for you.

 

Try going into the open firmware:

At power-on, hold down command-option-o-f

At the prompt type:

reset-nvram (hit return key)
When prompted for your password, enter it and press the Return key. (Note, just hit a return to leave it blank)
It responds OK.
reset-all (hit return key)
mac-boot (hit return key)

This works on a PPC mac, but I haven't tried it on an intel since the intels use EFI firmware.

 

You must alter the amount of memory in the machine before doing this.

If what you need is on the disk, you can just go out and get a cheap external enclosure, pull the hard disk in that Mac, and pop it in the enclosure.

 

I just removed one stick of ram from my friends mac, then it wqas gone, I was able to access the disk in terminal and remove a file to make a new account. (Note: I did this on a school bought laptop which can get you into a lot of trouble) Though, I'm not sure if it has to be a certain stick or not. I Just removed one because I remembered that its stored on the ram.