You should have received the <i>Quick Start Guide: Cisco Aironet 1200 Series Access Points</i> with the AP, anyway onlne <a href=”http://www.cisco.com/en/US/docs/wireless/access_point/1200/vxworks/quick/guide/12KDBQSG.html#wp6887″>you can read this</a>.
What I usually end up doing is turning the router into an access point. This way the router doesn’t have to handle any DHCP. Disable the DHCP server within the router, then connect the LAN cable from the wired network into one of the client ports instead of the uplink port on the router. This has worked on the several Linksys routers which I’ve done it on.