Cool! If you are sure this is the eeprom from this xbox. It should be simple to get back to where you were.
1) Download xbxhdm from the usual place.
2) Extract it, then place you eeprom into the eeprom folder, this is in the linux folder.
Now there are a million tuts for using xbxhdm so I am not gonna go into detail. If you have slayers or a backup of your xbox dash place it in Linux->C.
If you need a copy you can get it from slayers, use qwix to etract the iso. It is in the System->ALL->C.
3) Copy everything here and put it into the Linux->C.
4) Then double click
make-iso-win.bat it will then create a new file inside the xbxhdm folder called linux.iso.
5) Burn this as image using whatever you like, I like Nero
6) Connect you xbox hd to the Primary IDE, boot up, select option 3, type unlockhd -a, this should unlock the drive
7) reboot, go to option 1. Type xboxhd, select option 2, when prompted to copy files from cd type yes.

Reboot, option 3, lockhd -a.
Your done. Now you have a new drive with ms dash, do your softmod all over, no need to copy files to hd they should be there. Just try to luanch it from MA.