found this on the web (finally)
Flashing from a working DD-WRT to Tomato is much easier, as you can use the DD-WRT web interface. First, though, you need to get the password for the router. While you're still running the DD-WRT firmware, go to the command prompt, and telnet to the router. Assuming your router can be found at 192.168.1.1, you'd type "telnet 192.168.1.1" login to the router, then type this command "nvram get http_passwd". Write down the gobbledygood password on a piece of paper and keep it close by.
Go to the Tomato home page, download the firmware, extract it (you may need to use something like winrar to do this), and go to the trx subfolder. Inside, you'll find a file called code.trx. Rename this file to code.bin, so DD-WRT will recognize it as a firmware file. Don't worry, the router knows what to do with the code no matter what the extension is. Update the firmware, and type in the router address (probably 192.168.1.1). You'll be prompted for username and password. I think the default username is "admin" but it may be "root" Once you enter that info, you're in to the Tomato interface. Please note that the instructions for flashing the firmware via the web interface will only work once you've installed DD-WRT (or perhaps another 3rd party firmware).
