wickedfork,
There may be a firmware upgrade for your 5100 modem that could enable the bridge mode feature - still there is an alternate method.
Here's a better document page about setting that 5100 up with a router:
http://www.dslreports.com/faq/11827
The alternate methods should work.
However, THIS page states that the modem's default IP address is 192.168.254.254
http://bc.whirlpool.net.au/bc/hardwa...w&model_id=394
- John