I wanted to set up my Verizon Westell modem so that my router has the IP address and does all the networking functionality.  This makes administering my network easier.  After searching the internet, I found that lots of people had this problem but there didn’t seem to be any clear answers.  After spending a couple hours on the phone with tech support, I finally got it working.  Here’s my setup:

phone line–>modem–>router–>wifi/ethernet
modem: Verizon DSL Westell 6100F (but any modem with the Verizon firmware should work)
router: Asus WL-520gu with DD-WRT firmware (but any router should work)

Here’s how I did it:
1. Use a pencil or other pointy object to hold the reset button on the modem for 30 seconds.  This will restore the factory configuration so we can start fresh.
2. Connect the ethernet port of the modem directly to your computer.  Make sure your computer is set up to acquire an IP address through DHCP.
3. In an internet browser, open 192.168.1.1/verizon/redirect.htm .  This will bring you to a page that allows you to disable redirection.  Click the “disable” button.
4. Browse to 192.168.1.1 .  Now we need to set up the modem for bridge mode.  Click “My Network” at the top, then “Network Connections” on the side.  Click the “edit” icon for “Broadband DSL”. and then click the “edit” icon for “VCs”.  This will bring you to a page that allows you to configure the bridging.  Make sure that “Protocol” is set to “Bridge” and “Bridge mode” is set to “Bridge”.    Make sure it’s not set to “Routed bridge”.  That’s not what we want.  Then click to apply changes, but don’t let the modem restart yet.  We still have to change one more thing.
5. Click the “advanced” button at the top of the webpage.  Then click the “Private LAN” link.  The first checkbox should say something like “Enable DHCP server”.  Uncheck that.  We don’t want the modem dishing out IP addresses.  Then click “apply” to save.
6. We’ll need to turn off the modem now.  Turn it off.  Turn of your router too.  When we turn the modem back on, we won’t be able to connect to it any more to configure it.  Unplug the cable connecting your modem to your computer and plug it into your router’s WAN port.  At this point, I needed to call Verizon support to tell them to release my IP address.  If you don’t do this, your modem will still try to take the IP address.  I think you could get by without calling support by waiting a few days, but most likely you want internet now. =)  After tech support is sure that the IP is released, power on your modem.  Wait for the modem’s “DSL” light to turn solid green.  Then turn on your router.  If all went well, your router should now have an IP address given from Verizon.  If not, read step 7.
7. (optional)  If your router didn’t automatically get the new IP address, there’s a chance that it wasn’t configured the way we need it.  I have my router configured to get the WAN through “Automatic Configuration – DHCP”.  Yours might be different, depending on your router type.  Then, you’ll likely want your router to be a DHCP server for your LAN–by doing this, any computer that connects to your network will be able to get an IP address and get on the internet right away.