Update: Since writing this post in 2008 Linksys have produced v8.1 and v8.2 routers which may not be compatible with the instructions here. Luckily there are now 'official' guides for the dd-wrt site for v8 routers:

http://www.dd-wrt.com/wiki/index.php/How_To_Flash_the_WRT54Gv8

http://www.dd-wrt.com/wiki/index.php/Linksys_WRT54G_v8.0_%26_v8.2


Many sites say v8 of the WRT-54G routers cannot be flashed with DD-WRT. I have now done this twice and here are simple instructions - these are re-worked from bauer-power who's post I came across when fearing my first attempt bricked the router. First try on a v8 took me over two hours mostly in Google/ Forums, second time about ten minutes with these steps:

  1. Go to http://192.168.1.1 (default user/pass is admin/admin)
  2. Click on Administration tab, then click on Firmware Upgrade. Upload vxworkskillerGv8-v3.bin
  3. When you see 'Update is successful, Rebooting....' unplug the router for 120 seconds (some say to wait 120 secs BEFORE unplugging - do both to be safe)
  4. Plug in router, ping 192.168.1.1 to verify it is still alive (you may have to hardcode static IP settings on your PC to have a gateway of 192.168.1.1, subnet 255.255.255.0 and IP 192.168.1.100 )
  5. Run the Linksys Tftp Utility, uploading dd-wrt.v24_micro_wrt54gv8.bin with these settings:
  6. Press Upgrade. When the upgrade GUI's green dot appears press the router reset button
  7. Browse to 192.168.1.1 and see the new firmware (default user/pass is root/admin)
If you are looking to flash another a non v8 router with DD-WRT I found these links to be the most helpful: DD-WRT Installation wiki Client Bridge Example (this is almost 100% correct for V24 firmware - you should have no problems following it)

Also be aware there are version specific firmwares on the dd-wrt website, but it may take you while to find them: Linksys is under the Broadcom (chipset) folder. More than likely a newer builder than I linked to will work with the v8, but I simply wanted another client bridge and have had one running with v24 for two months now.

Afraid to do this 'hack'? Of the three Linksys routers I've flashed none became bricks. Heck they are only $40 now anyway, but if you do brick one it looks they are not too impossible to recover:
Recover from a bad-flash (unbrick a dead router) wiki

So Why did I do this?

This was left to last as the news that we can flash Linksys routers is years old. Still even me -a tech blog addict- was still not 100% sure what a wireless bridge is, and how to link to wireless networks into one seamless network. We need access points in many locations, but are renting so cannot run cat5 everywhere. Yes I could buy custom wireless adapters for the xbox (xbmc), HTPC, NAS drives, PCs and printers but they normally cost $80 or more each and are no where nearly as flexible as a DD-WRT flashed router which has 5 ports. Also the new V8 WRT54G router I bought for my theater room was losing the plot when the PS3 was turned on - I have no idea why but the voip phone etc would all lose their connection. Since being flashed it has been 100% stable.

This is a sample wireless bridge, to the machines it looks like one seamless network:

We now have three WRT54 routers with DD-WRT. One is a primary and two more are client bridges.. one for the xbmc and for my main PC in an office room. They seem to play fine together. The two client bridges have five Ethernet sockets as the wan port was reconfigured by DD-WRT. This is fantastic for many reasons, e.g. when moving large files I can plug a laptop or NAS drives into the same wired network. WiFi is fine for streaming media, but you trying moving a 10GB VirtualPC image or 4GB TV recording over WiFi and you'll see how much faster/ reliable wired networks are.