Assuming you have a "vanilla" NSLU2 (ie straight out of the box) the process to replace Linkys firmware with the Unlsung firmware is straight forward.

1. REMOVE HARDDRIVES !!! This is important
2. Access the NSLU2 web interface administation page (default is 192.168.1.77, but the IP will be dependant on your network)
3. Enter the Administration menu link -> Advanced -> Upgrade
4. ENSURE HARDDRIVES ARE REMOVED!!!!!
5. use the web-interface to browse to where the firmware is found
6. click upgrade and wait [approx. 5 minutes]

Once the firmware has been updated and the NSLU2 has rebooted you should now see the web-interface page has changed slightly

• the Linksys logo is now the Unslung logo
• firmware version top-right is that of what has been uploaded
• centre-bottom there is a label stating that the NSLU2 is running from internal FLASH (need to unsling next)

Now if you already have a version of Unslung in the NSLU2-FLASH then the update procedure is a little more involved