This is the keyboard port used on the back of the Mac in question:
So the question is: Does YOUR Mac have this port? If not then no it won't work. Can't seem to find anything relating to old school Mac keyboard port to USB adapter either.
Sooo...yeah. I'm going to say this is a no-go. Don't take my word for it though, see what others have to say. I do know the Mac K/B port is NOT a PS/2 port...might be compatible though?