I will say, while I like Amplitube (much more so than Guit Rig), the process to utilize the Custom Shop if your studio computer is not on the internet is the most convoluted, cumbersome authorization process of any piece of recording software I've ever owned.
Numerous posts on the IK Forum will back this up numerous times over.
And, yes I know it's free, but I own a purchased copy of Amplitube 2 as well as a couple of other IK products.
IK makes some very good plugins but everything from the new website (better than the old one) to the authorization processes are less than user friendly.
And yes, I've read the several page offline auth instructions. It is not a few simple mous clicks. I would post it here but it's way too long.
"Musicians first!" Maybe, but definitely not professional audio engineers first....and that's a shame.