Hello Kevin,
You will need to setup the DMZ interface in a different subnet using an address range from RFC1918 (192.168.0.0-192.168.255.255, 172.16.0.0-172.172.31.255.255, 10.0.0.0-10.255.255.255) and then NAT traffic from the 'dmz' to the 'outside'. You will also need to modify the access-lists accordingly.
Please post your config and I'd be happy to get you pointed in the right direction, also -- please indicate whether you are using a base or security plus license and what software version you are running (both items can be found by issuing "show version").
-Mitch