This is just speculation on my part, but it appears to me (looking at an upgrade file at hifi-remote.com) that the Apple long press doesn't send a signal of long duration. Instead, apparently it simply sends a short signal when the key is let up. If the press was a short duration, then it sends one IR command, and if the press was long, it sends a different IR command.

If that is true, then you can teach any learning remote the two commands (to different buttons, of course). Probably pretty easy to check by looking at the output of the Aple remote with a digital (e.g. cell phone) camera, and seeing when the IR is being sent, and if it lasts for a long time.