So I can enable DHCP on the Linksys, but just give it a different range?
No, just disable DHCP Server on the Linksys -- it actually did that automatically when I selected "Repeater Bridge" as the base configuration. The part I missed at first though, was to fix the IP address of the Linksys, to be in the same range (subnet) as used by the other router.
I've done that "Site Survey" and "Join" part, and I saw the Airport's SSID and chose it, but it never works after that...
Mmm.. well, you're right that the problem is there.
The DD-WRT firmware I'm using here is whatever was current when I got the thing:
DD-WRT v24 RC-4 (10/10/07) std.
Cheers