If the xbox still works with just the video screwed, try creating a Configmagic bootdisk and try and run it blind, the program will change the front LED for the purpose of restoring an eprom in this way, so at least you can use this to indicate that the program is booted correctly from DVD.
Just go through the motions on a functioning Xbox and take down the keypresses...
Another option would be an Evox bootdisk, get access through FTP and copy evox to the harddrive, modify the evox.ini on the harddrive so that the first or only menu option is Backup. Create another Evox bootdisk that has the first or only menu option to launch the Harddrive Evox .... once you boot with the second evox disk press A, wait 10 seconds, press A again and voila .... Eprom back up and HDKey on your harddrive, unlock with atapwd and off you go.