Advanced pricing for service line in Contracts

Can we use the custom code (attribute mapping, pricing formula etc) for service line in service contracts? It works for usage but not service.

For usage lines, the billing program calls the custom package where all the pricing attributes are created and returns the calculated rate/amount. This works based on modifiers and qualifiers.

But for the same contract, the service lines do not call the pricing code. Is there a way to have the service line call the pricing code and return a code calculated amount?

If not, is there a way to update the billing stream of a contract line so that it does not bill future invoices?