Any learning remote should do. The Apple Remote uses standard IR signals rather than IRDA like some B&O, Pace and other stuff does.
I have programmed mine into both a Philips Pronto and a Denon Surround Amp learning remote.
The trouble you will have will be finding a remote smaller enough!
Easy solution - buy a Mac Mini (or two), a iPod Hifi or a Mac Book (Pro) and you get another remote. I did all the above!