complicated router question....

I don't recall seeing anything regarding the type of DSL modem you have but
every Cisco router and switch has a password recovery technique <evil grin>.
The 675 uses the 6xx series recovery process available here,
http://www.cisco.com/warp/public/474/pswdrec_6xx.html
as well as several other places assuming this one doesn't work.
Sorry not on Linux machine at the moment :(
HTH,
John