Hi,
Please reference this document:
http://cisco.com/en/US/tech/tk175/tk15/technologies_configuration_example09186a0080093fbf.shtml
It is written for the 1700 but will work for any router. Ignore the "6400" part.
Note, certain commands are not needed with IOS newer than 12.2(13)T
Since you are using quite a sophisticated router, you can also look in getting a WIC-1ADSL card that will let you connect directly to the ADSL line, eliminating the ISP-provided modem.
Hope this helps, please rate post if it does!