I literally walked in with the Galaxy Nexus, gave them my account info and they got me a micro SIM and activated it. You could do the same over the phone, but then you'd have to wait for them to send you a micro SIM.
Aww crap. My grand strategy was to order a new phone using my girlfriend's upgrade on our family plan, swap SIMs/phones, and call it a day. Looks like I have to get Big Red involved. Why couldn't it be as easy as T-Mobile/AT&T? There's no reason for it not to be.