I may not be of much help here, as I have not done this with BellS. But here are some things you can collect before starting to configure. You will need to get your PPPOE username, password, PVC numbers for the ATM interface to use, and yeah of course their toll free support number. I have done this with SBC DSL and its not a huge deal of configuration to be done before getting the circuit up and running.
Rest all should be the same as mentioned in the link.
http://www.cisco.com/en/US/tech/tk175/tk15/technologies_configuration_example09186a0080093e67.shtml
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus