Just tried to get it going on my Newnet connection following the advice from here and it kept complaining of invalid PPP username.
Newnet appear to have sdsl and adsl subdomains in their PPP authentication (presumably so the traffic is steered to the right edge router) so in my case the address is @adsl.newnet.co.uk
What firmware does your router have?
V5 = run the Set up routine from the HOME page ( 192.168.1.254 )
V6 = just enter your details and the router password on PPP login page (http://192.168.1.254/xslt?PAGE=HURL13)
Ihave had trouble with the 2wire not excepting from the Broadband Link Advanced Settings page but if you use the wizard on the system summary page bottom right that works.
It sounds like you needed to use the javascript method to get it to accept your details. :)
Tried that, had none of it
Can Newnet see what's happening on your abortive login? Usually, when this has happened to me its because I've typed something incorrectly.
When I checked the Newnet setup details it uses vanilla BT Broadband settings.
Reset the router to factory settings which are those used by Newnet and try again at 192.168.1.254 or http://192.168.1.254/xslt?PAGE=HURL13 depending on your firmware version.
I shall give it another whirl when I've completed my current assignment.