Hello Giulio,
I'm not sure I'm understanding your question, but let me give it a shot.
The ACE module won't actually "connect" to a Nexxus switch. From the ACE's perspective, as well as the Catalyst switch in which it resides, the ACE is connected via a Tengig port across the backplane. In your Sup's config, you allocate VLANs to vlan-groups, and apply the vlan-groups to the ACE. From your ACE's view, it doesn't know what the view is beyond this Tengig port (we only call it a Tengig port because there is no 16Gig port name).
So while I'm not sure if this was tested in a lab, I can't think of any reason why you couldn't have a vPC between the Catalyst 6500 and your Nexxus 7000.
Hope this helps,
Sean