Daniel, I also recently installed a WRT on the Linksys WRT54GL. But I used DD-WRT instructions - went to http://www.dd-wrt.com/site/support/router-database, entered my model number and got direct download links to the firmware along with a README.
One very important points in flashing these routers is to clear the NVRAM by doing a hard reset BEFORE and AFTER an upgrade to a different type of software on the device. Also, starting with a micro build is strongly recommended.
In any case the hardware looks to be very solid, especially if you don't need gigabit ethernet and n wireless, but might need some advanced networking features.