Custom firmwares like DD-WRT, OpenWRT and Tomato allow you to set up your own local DNS server under the form of a
hosts file. It's ilke a
hosts file on an OS, but then it's shared among all computers which makes it easier as you only have to change it in one location. All computers should be configured to have the router as DNS server in order for this to work.
According to the router database of DD-WRT, your router is not currently supported as it has no Ubicom support. Another incompatibility list of the same firmware can be found at this URL which shows at least three revisions of your router that are incapable of this firmware.
I don't know about the two other firmwares as I don't have much experience with them...