For a howto see section 15.9 here
The dd-wrt standard release has seen stable for a couple years however the project is still very active including new routers.
Please consider before you buy - at this point in history you really want 802.11n and there are already routers out for very new 802.11AC (up to 500mbit) . You MAY want to delay that purchase a couple months if you can.
The other issue - you probably want a router to support IPv6 at this point. The standard dd-wrt is based on a 2.4 kernel and does not support IP6v w/o addin tools and utils a a 'special'. There is a dd-wrt variant that supports IPv6 and is base on a 2.6 kernel,but IIRC it cant run on many legacy routers (insufficient dram).
Here is the router database - enter asus or cisco or ... and hit return.
I haven't surveyed soho routers in a while but both Asus and Linkssy-Cico are making some nice *looking* its, bti do our homework.
Just to add complexity, I'd be investigating other router firmware too, like OpenWRT.
The TomatoUSB project also get a LOT of good press,
But also ....
This place does a nice job reviewing routers, but ... likely w/ mfgr firmware unless otherwise noted.