That's exactly what I did for IMC 09 and I got lucky and got in. Start refreshing the page a couple of minutes before it goes live so you can hopefully get in right when the page goes online. Also make sure that your Active account is up to date so you don't have to make any changes during registration.

Now, whether or not Active.com will stay up long enough for you to register will be another question. Good luck.

I got into IMC on the second round of online openings (good since I couldn't make the trip to registration this time since I was on vacation) The first time I was to slow. Don't assume because you get onto Active, and into your account you are in (what I did). Get the basic info in. I copied/pased cc info from word so it was right there. Only worry about filling in the REQIRED starred information.
Good luck.

CDA and Arizona are the 2 that have not filled up immediately that I know of. The others do, infact this is the first year that I can think of that IMC had online registration. The 2 times I have done it, had to go up to register. I think now that Arizona is later it will fill up quickly. CDA is still pretty early in the season, which I think makes it a bit more questionable for people (at least myself, I would have to be doing century rides in freezing rain).

I believe one of the main purposes of this is to discourage people from "signing up"/getting a certificate/whatever you want to call it unless they are committing to do the race. From what I understand, if you decide not to do it after that (and after you have paid) you are subject to their refund policies. If they were going to give out full refunds at that later time why bother collecting the money then?