I've only seen one REDCOM switch in real life, and never actually worked on it, but it needed a funky line card in the PC to control it. If you've got the kind with a MCI card that has an RS-232 port you could get something like zTERM and a USB-to-Serial adapter for your ibook. I don't know enough about REDCOM's to say more than that.
Cheers,
Rich Whiffen