Download the patched Cromwell image
Download the EEPROM patcher
Unzip the image and the patcher, put both in the same directory with your EEPROM image, and patch the Cromwell image with your EEPROM : addEeprom cromwell-patched.bin eeprom.bin
Program your mod with cromwell-patched.bin
Boot your box and wait a few seconds - you should see a message "EEPROM flash - status : SUCCESSFUL"
Your EEPROM is now restored, you can turn off your box and reflash with your favorite bios ... or install Linux :) As a side note, if you want to install Linux I'd suggest you to download an official Cromwell image as I'm not sure of the quality of this build ...
Diff to Cromwell
Note that you'll need a fairly recent gcc to build Cromwell - 3.2.3 seems to generate something consistant if not perfect :)