As one of the driving forces behind the SCRIW off-season competition in South Carolina: Start small!
Get a strong one- or one-and-a-half-day event going, then talk about crazy expansions. Also consider this a 2014 project; this gives you plenty of time to get teams on board for what is tricky to start up. Check
this paper out as a great starting point, and attend some if you haven't. (I went to well over a dozen over the years before the first SCRIW competition!)