But I believe that the BTagent does not use the same vlan (tagged 101), etc, that is the normal end-user's conduit. The BTagent uses a totally different mode of communication with the ACS, via the vlan tagged 301.
I would be tempted to connect up the ECI B-FOCuS /r modem only, allow it to synchronise with the cabinet DSLAM and then leave it in that state over night. Next morning either connect a system directly to the modem (which would require the system to establish the PPPoE session) or connect the router to the modem. Then check to see if a PPPoE session is established or not.