You are stuck using it. However...you can still use your own router...and set it up so your router obtains the public IP address (thus avoid double NAT)
I have U-Verse..and I frequently play around with different routers, mostly different *nix firewall distros. I always am able to set them up as the edge device.
On your own router, on the WAN interface, set the "host name" to what you want. For example, right now, mine is called "PFSense". Original.
Now..make sure that the LAN IP address of your own router is NOT 192.168.1.1...most notably that 3rd octet....because the 2Wire unit is 192.168.1.254. So make your own routers LAN IP something like 192.168.0.1 or 192.168.10.1...just as long as that 3rd octet is different. Also make sure your own routers WAN interface is set to "obtain auto/DHCP"
Now...uplink WAN port of your own router to one of the LAN ports of the 2Wire unit. You will not have anything other network devices plugged into the remaining 3 LAN ports of the 2Wire.
Have a computer plugged into your own router now...log into your own routers web admin..make sure it has an IP address from the 2Wire on its WAN interface..at first it will pickup an internal IP from the 2Wire like 192.168.1.100..this is fine, and expected. Just..make a note of that IP.
Now...from your computer, log into the 2Wires web interface...
http://192.168.1.254
Go to the Settings tab
Go to the Firewall tab
You'll see a list of devices connected to the 2Wire..that pulled an IP from it. You should see the IP address that you noted your router obtained from it..perhaps you'll see the host name next to that. Highlight that...so that it says "You have chosen...xxxxxx"...with XXXXX to mean your routers WAN interface. Now..scroll down..put a check in the radio button for "Allow all applications (DMZ Plus Mode)..and click "SAVE".
Also while you're in there..disable the wireless of the 2Wire.
Next...open up another tab in your browser and log into your own routers web admin...release and renew that WAN interface. It should now pick up your public IP address instead of the 192.168.1.100 it had from the 2Wire. What this "DMZ Plus Mode" does it pretty much bridge the 2Wire so it passes the public IP to the device that you specified in that DMZ plus mode. The 2Wire memorizes the MAC address of the WAN interface of your router when you do that setup above.
Sometimes you have to run through the two or three times until it sticks, but I've always gotten it to work fine.