Michael, you could (but I guess that's too late now), add this to the first start license checking of MoI. This way you'd spare yourself the hassle to setup a page or email licenses to people. I mean, MoI asks for a license on the first start anyway. If it then detects a v2 license (I don't know if you encode the purchase date in the license code), checks the date and automatically generate a v3 license.
On the other hand I am not sure if you want to ship the license generating code with MoI. Some idiots could try to crack it.

However, I just asked because I can't wait. Never saw v3 and I don't know anything about the new features. Maybe I'll try the beta in the mean time :)