Looks like we have the answer. Per Verizon chat. I actually don't think it matters, as both should probably work. But I think I'll do it this way.
He says you CAN activate and then call, but the question is do you HAVE to activate the dumb line and then have it switched back? I would prefer to just call and have the iPhone activated on my line without the headache of the 'swap'. This is the one instance I'm a *little* happy to be getting my iPhone a week later than launch day...at least I'll know the proper protocol the day I receive it...