Friendly Neighbors and Family like to share...

Okay, I'm trying to replicate a system I installed in my home a couple of years ago for my use for my cousin in her house.
With permission, I am able to use my neighbors protected wifi when mine flakes out. I use two tomato firmware wrt54g routers (tomato does everything but it tooks me weeks to figure out my setup and I'm trying to avoid doing that again). The first one accesses my neighbors 1.5 dsl wifi (from 300 feet) and feeds and goes into the second unit (different subnet) that connects to my router by ethernet when my cable internet doesn't work.
I need to do the same for my cousin who also permission and has been using her mother in laws internet for several years. Problem is the connection is flaky.
I want to use Mom's internet and use it a the source for cousins separate network.
I bought a refurbed netgear wnr3500L and hoped to do it with only one router.
Mom's router is a older airport extreme which does not do wds repeater mode at all well . So I just want to snatch her network signal (85 feet) and 'repeat' it to the new wireless network. I would be willing to buy a second router to do the repeating, (my cousin is worth the expense, I'm paying).
I tried at first to implement my hardware on hers and realized I should try different new hardware.
Long question, I know. Anybody willing to give this a try for advice?

You need ddwrt in you wifi router (if its supported). Most off the shelf wifi routers do not support bridge mode, which is what your trying to do. When your DSL connection goes out, you would manually have to set the router to bridge mode.