Skynet Repair Kit Bootloader if you need a CFE the Bootloader Creator can create one for you.
Use Bootloader Creator to create cfe for your router.
Download install and do a online update before you create the cfe. 
Your Mac is on the bottom of the router.

If you can't create the one you need with Skynet Repair Kit Bootloader
You get one here or request it here http://www.dd-wrt.com/phpBB2/viewtopic.php?t=25971
or 
DD-WRT Forum Forum Index -> Broadcom based hardware
http://www.dd-wrt.com/phpBB2/viewforum.php?f=1


If the CFE that you need is not here or the 
Skynet Repair Kit Bootloader can't make it.
You can request one in the forum above.

For Example you would post in the forum 
"WRT54GS V6 CFE.BIN needed"



Setup The Software:

tjtag
Extract tjtag. Once tjtag is extracted copy the giveio.sys that is located in tjtagv2-1-4\windows directory, to the C:\windows\system32\drivers.

Note: The skynet tool can supposedly do this automatically but always fails, so you better off doing it manually.

Execute the loaddrv.exe to load the tjtag driver.
Skynet tool can also do this, if you want to use a GUI skip this part and goto the skynet section and read about the "Parallel port driver loader".

Skynet
Install skynet
Open the "Bootloader Creator"
Check for updates. Click "Online Update"
Click "Seek for Updates"
Click "Cancel"

To load the driver using skynet, open the "Parallel port driver loader"
append the path c:\windows\system32\drivers\ with giveio.sys

example:

c:\windows\system32\drivers\giveio.sys

Click "Start", the driver should now be loaded.

Hook up the router via the JTAG cable to the parallel port. Open a CMD and make sure you're in the same directory where the tjtagv2.exe is located.

Execute this command "tjtagv2 -probeonly /noemw" (without the quotes).

If you get a response showing the chip set and flash info, then you've successfully installed the JTAG header and the giveio.sys file.

Now that the JTAG is connected and the driver is loaded, do the following:

Note: If erasing doesn't work the first time just Ctrl + C out. Power cycle the router and try again.

Make A CFE File With Your MAC Address.
Open Skynet "Bootloader Creator"

Select your router and version from the drop down list.

Enter you MAC address in the "Devices Labeled MAC Address"

NOTE: If your ISP gives you an IP based off of you mac address, you will need to set the MAC address -1 when creating the CFE.BIN.

Example:
If your MAC address is (the MAC that is needed) 00:0F:B9:AA:D1:C2
Create the CFE.BIN with the MAC Address 00:0F:B9:AA:D1:C1
By doing this your Wan MAC Address will automatically be assigned 00:0F:B9:AA:D1:C2 when the WRT54G is flashed.

Click "Create CFE.BIN"
Save the file in the same directory as the tjtagv2.exe