How to use Airport Extreme with CenturyLink DDR2200 DSL Modem in Bridge Mode

Goal: Access the internet through the following sequence of network devices (in this order):

- Devices (Macs and otherwise)

- Switch

- Airport Extreme Base Station (NOT in bridge mode)

- CenturyLink's Cisco DDR2200 DSL modem (in bridge mode)

Reason: Our credit card merchant account requires quarterly IP scans to make sure our network is not accessible. WIth our old DSL modem, we passed, with this Cisco DDR2200 (CenturyLink's "Core Connect" service), we fail. I want the AEBS to be our firewall, and possibly allow us to pass inspection.

Problem: Centurylink says our bonded DSL line does not require PPPoE name and password, so there is no account data to enter in the AEBS.

Question: How can I get the AEBS to access the internet through a bridged DDR2200 modem, if I don't have PPPoE settings?

Thank you,

Bart