rccpgm,
Yes, QinQ or l2circuits would work in this situation. The issue was that the existing infrastructure is setup Layer 3 between the buildings. Thus they were not in a position to do the standard VLAN methods which they well understand.
The solution then could be to use standard metro ethernet services to transport layer 2 across a layer 3 network. QinQ and l2circuits are supported on EX switches. The other method using VPLS may not be available on an EX infrastructure.