here im work i have 7600 with 4 STM's .
in that STM's i configured an primary interfce called ATM1.
after that i configure sub interface ATM1/0.1. this interface is virtual and i can assign an IP address for him , encapsulation ( ll5snap the encapsulation of the ATM ) and the route bridge command.
in the other site (CO) , i will put equipment that can encapsulate the intire packet and changed to packet that can cross the cable with ll5snap encapsulation.
i don't know if my explanation is good , but u can understand it in this site :