Okay, I opened up my config.plist, and noticed that I had no board serial number or smuuid, which is why I was getting the "error occurred, try again" message. I replaced the MLB and ROM with my Air's, and lo and behold, I message immediately worked after a reboot. I don't want to risk screwing up imessage on my air, though (I barely use imessage anyway), so I went back to my hack and replaced my air's MLB and ROM with random ones I made up. Now, I get the please contact customer code (which won't work based on what I'm reading here). So, if you're getting the "error occurred, try again message", make sure you have an MLB and ROM and SMUID if using clover (and the equivalents in chameleon). With that, you should be able to get the contact customer code. However, contacting apple won't work. For now, replacing MLB and ROM with that of a real mac seems to make imessage work (in my case, I didn't even get the contact apple customer code, imessage just worked after restart).
Hopefully we can find a way to avoid having to use a real mac's MLB and ROM, as I'm afraid that apple will just tighten up security in the future and block out any computers, real mac or not, using duplicate MLB and ROM's.