The other day I atempted put OpenWrt on the D-link DSL-502T gen II (telecom issue model) It worked, and is running fine http://oldwiki.openwrt.org/OpenWrtDocs(2f)Hardware(2f)D(2d)Link(2f)DSL(2d)502T.html gives intrutions for the gen I model only difference is that it has a different mtd layout (which means the upload script doesn't work) so you need to manually upload it to the flash using an ftp client and adam2 or rewrite the upload script(it's in perl) http://www.seattlewireless.net/ADAM2#ADAM2FTPaccess gives a good explaination of how to upload it, and also read the comments in the upload script they will tell you how to setup the mtds also the build enviroment is like 2GB's so downloading takes awhile
also the default firmware(from d-link's website) for the gen II doesn't seam to work so if you do try openwrt probably a good idea to back up a flash dump before hand feel free to ask any questions WARNING: ftp on ubuntu seam to go extremely slow and will take ages to upload, best idea is to backup the webpages and dump them to a local file, then boot in to windows and use it's ftp client DISCLAMER: you can and will brick your modem during this, don't blame me please, just read everything and understand it before you do ANYTHING
