1.0.2 to 1.1.1 with iTunes 7.5

I have a 1.0.2, i want to virginize it in order to be able to upgrade to 1.1.1

I am on a mac with itunes 7.5, without AT&T simcard.

Can this be done and if so, which guide should I follow? It's quite confusing with so many methods out there.

Thanks.