Connecting a Cisco WAP to an AT&T modem/router?

Howdy,

At a small business I help with they have recently gotten internet. It's from AT&T and they have a BGW210 modem/router. The device has the ability to setup a "Home" SSID and a "Guest" SSID. The Guest SSID is setup as "Internet Only" from a dropdown box. This all works fine.

However, the range of the modem doesn't reach into the far end of the building or into the 2nd level. We really only need the "Guest" network (for internet only) available in the remote locations. All the office work is within range of the main router. So, I thought we could add in some Cisco Access Points to extend the network. I have two Cisco 1142 WAPs and am not sure if or how I can configure them to work with the AT&T router.

I don't know how the inner workings of the AT&T router work to know if I can setup these WAPs to work in conjunction with the router and am looking for ideas. If anyone knows how I can potentially set these up so that people have internet access from the main router and the two WAPs, that'd be great.

Thanks!