Sharing USB modem via ethernet to router.

Hey,

I need to share a USB modem (anydata adu-310a) which is plugged into a macbook pro. I can share the connection via wifi but it's a bit sketchy sometimes. I have a wireless router and I'd like to run an ethernet cable straight to that and then have that broadcast the signal. When I plug into the router it gives my ethernet port a self assigned IP address. The internet light comes on the router but nothing gets broadcasted in terms of internet. I have tried a netgear and a linksys router. I'm assuming it would do the same thing if I had a USB dsl modem and was trying to share that connection via ethernet to a router.

Any ideas on how to get them to talk together? If I plug into the internet port on the router I can't access the router setup (because I'm on a self assigned IP) but if I plug into port 1 I can, but of course then the router doesn't pick up the shared internet...

Thanks for any thoughts.