Linksys WRT54GS v3.0
From DD-WRT Wiki
 How To Flash
Need confirmed instructions posted
 Other Notes
[Comment added 05/03/06 by PhoneBoy] On my WRT54GSv3, I found that the device wouldn't take ANY firmware unless I reset it using the button rather than just factory reset from the web interface. Word of warning. I was able to download and install the firmware for the purposes of getting vpn up and running. The firmware installed and everything is as before. however, still no vpn.