WDS with Vodafone (Huawei B970) and Linksys WRT54GSv7 running DD-WRT

The commonest mobile broadband offerring from most operators is some form of USB dongle (with a data-enabled SIM card inside), which unfortunately limits sharing that internet connection. Welcome the Huawei B970 HSDPA wifi router. A buddy grabbed it for me from Pretoria for 2500ZAR, quite a decent price considering its functionality.

I got a cool place for it in my house, somewhere, some hidden corner upstairs, that's the only place I could get 3G+ HSDPA coverage. Unfortunately, this was not the ideal location for covering the entire house with WiFi.

I grabbed my trusty old Linksys WRT54GS v7 already flashed with an older version of DD-WRT micro, upgraded to DD-wrt v24-sp2, and set it up as a "wireless range extender" or "repeater" or whatever one may call it. Using the stock Linksys firmware, this functionality is not possible.

Step by Step:

1. Setup the Huawei (aka Vodafone) B970 router, make sure it can properly serve wifi (and net connectivity). It's a lil bit tricky, you need to create a profile for your operator (you must be equipped with your APN + user-name and password if required), then set this profile as the default. The vagaries of this step will not be covered here - refer to the packaged printed manual (in the box).
2. Grab your Linksys WRT54GS (or any Linksys wifi router with a broadcom chip). Flash it with DD-WRT, the latest build. Instructions to do this are galore on the dd-wrt website. This is a trivial process, depending on the Linksys router you have. If you are wary of this, then just buy the Linksys WRE54G. However, adventure is fun. Congratulations if you have come this far, and are ready to proceed :-)
3. Open the B970's admin interface, go to advanced wireless settings, go to "wireless bridge", enter the MAC address of the WRT54GS. Do not get the MAC address at the back of the Linksys, but in the dd-wrt WDS page. (Wireless -> WDS)
4. Open the dd-wrt Web UI, turn off the WAN interface, DHCP and firewall. Ensure the SSID, channel and security settings in the Linksys match those in the B970. Go to the WDS menu, enter the MAC address of the B970 and select LAN. Note the MAC address listed atop and ensure its the same address in the B970. Enable "Lazy-WDS".
5. In the Linksys "Basic" setup menu, enter the gateway and resolver IP address of the linksys as the IP address of the B970. By this time, I assume you have already setup the two routers to different IP addresses on the same subnet.
6. Important: Make sure they are in the same channel.
7. You should be good to go. When you open the "status" page of the Linksys, dd-wrt should show you the online 'WDS Nodes'.
8. Leave a comment and I'll help you out if you are stuck. I've been rather lazy to add screenshots from both routers' setup.