Contribution to make multiple sores share a payment module

[msfalcone]

I am trying to make two sites run off the same merchant account. The bank account involved is overseas and is very expensive. So, i want the sites to be related in only the payment module. They must have different shipping, tax, and catalog. Is there a contribution to do this? or would I need to edit the database of each site seperately? Or could I build a common database that serves each of them? Thanks for any help you may be able to offer.