Here is how I managed to install OpenWrt on a WRT54G V5.0 (with 2MB flash and 8MB RAM).
Some might argue that what is the purpose and the things that you can do are limited. But if you have such device and you want to do something more than the stock firmware can do here is the way.
I used the following procedure which is meant for DD-WRT:
and this forum post as guides
I will quote the steps from the above procedures with my adaptations:
(However please read the above procedure completely to understand the whole process before you start following the steps given below).
1. You need to have the OpenWRT micro image to start with. Two ways to get it.
a. Directly download from http://downloads.openwrt.org/whiterussi … uashfs.trx
b. Go to http://wiki.openwrt.org/ImageBuilderHowTo and setup your build environment and build the image yourself. The advantage of this is that once you have flashed the initial image successfully, you can start experimenting by adding additional packages to the image itself and reflashing.
Make sure that you use the image with .trx extension in the steps given below.
2. Download vxworks_prep_v03.zip and extract.
3. Download vxworks_killer_g_v06.zip and extract, OR create a custom firmware image with your MAC address embedded in it.
See the 'Changing your MAC address' section at http://www.bitsum.com/openwiking/owbase … RT54G5_CFE.
4. If you don't know how to use (or don't have) a console mode TFTP tool (i.e. tftp.exe), download the Linksys TFTP transfer tool from ftp://ftp.linksys.com/pub/network/tftp.exe
5. You will want to assign your network adaptor a manual IP address, since you may loose your automatically configured one and have trouble TFTP'ing the firmware. To do this see the troubleshooting section or google it. It's done at the properties dialog of your network connection, in the 'Internet Protocol (TCP/IP)' properties.
6. Go to your router's web based interface and enter the 'Administration' tab. Then select 'Firmware Upgrade' and choose the vxworks_prep_v03.bin file. Hit apply. After a minute, your browser window will go blank. At this point, power cycle your router.
7. Again point your web browser to http://192.168.1.1. You'll see a different sort of firmware upgrade screen. This is the Management Mode. Select and apply the vxworks_killer_g_v06.bin firmware upgrade. WAIT for your browser window to turn to report 'Success'. Have troubles? Try a different web browser, the http daemon in management mode is very finicky.
8. Now unplug the power cord of your router, then plug it back in. The power LED should now be blinking.
9. Now you need to do a binary mode TFTP transfer of OpenWRT micro (openwrt-brcm-2.4-squashfs.trx) to your router. To do this you can use the Windows TFTP console mode utility, the Linksys TFTP Windows GUI utility, or some other TFTP client. You may have to disable your firewall if by some chance it is blocking outgoing connections on port 69. Many TFTP clients don't default to binary mode, so be sure to specify it (i.e. the -i switch with the Windows console mode TFTP utility).
o For Windows TFTP console mode utility (example, adjust accordingly):
+ tftp -i 192.168.1.1 put openwrt-brcm-2.4-squashfs.trx
o For the GUI utility
+ simply enter your router's IP (192.168.1.1), select openwrt-brcm-2.4-squashfs.trx, leave the password field blank, and initiate the transfer.
Do NOT reboot your router after TFTP'ing, this will happen automatically. It takes a couple minutes after the TFTP transfer finishes for the firmware to actually be flashed.
Skip to 'finalizing' or 'troubleshooting' sections from http://www.bitsum.com/openwiking/owbase … RT54G5_CFE depending on the outcome.
I am hoping to experiment more on things that you can do with this box and will post here my findings.