Great forum, been lots of help. But I need more

I had my 7800DXL working fine with Sky ADSL up until a couple of weeks ago when it kept losing connection. I think Sky are messing with the settings at my local exchange so I want to try using the SR101 as just a modem and then use the 7800DXL for everything else (for the moment, always want to go back to JUST the 7800).
When I set the 7800 in bridging mode it all works fine apart from not allowing me to switch on DHCP. I suppose this is by design...? Anyone know if it's possible to run the setup I want i.e. SR101 modem only, 7800DXL everything else (wireless, DHCP, etc)?
Thanks,
Ratsy