This may be something similar to what I went through with the Linksys repeater. The default address is WAY off the normal subnets used for home networking.
So. Here's what I had to do.
Write down all the settings for wireless operations on the primary router. Change the IP address from DHCP to Static on the notebook, and change the IP address manually to talk on the same subnet that the repeater was set to. In other words, your standard Linksys router normally resides on 192.168.1.X, and the repeater is on 192.168.2.X, change the IP to 192.168.2.10.
Hardwire from the computer to the repeater and then log in to it via your browser. Change the IP address on the repeater to reflect the subnet it's going to reside on. (If your router is 192.168.1.1, change the repeater to 192.168.1.2.). Set up the secure settings to match the router, then save all settings. Go back to the TCP/IP settings on the computer and change the IP back to DHCP.
Yeah, the repeater came with an "Easy Setup" CD. It wasn't worth the price of the plastic it was burned to. Totally worthless. You may want to do this via Windows as well, as I find it easier to make TCP/IP changes to the computer with that OS. Once you have the repeater set up, you should be able to nail it easily from Linux.