I have a softmod and this is the guide i followed, it mentions certain folders that are specific to the UDE mod, so if there is anything different on your box, point it out and i'll tell you what to do, i have just modded a fex boxes using this method. So the knoledge is fresh in my mind
How To Install A Bigger Hard Drive
Using this method you will not need to do anything to your original hard drive which means that if anything does go wrong you will still have an xbox :-)
1) xboxhdm 1.9 (Found at xbins’ in the directory: /XBOX/Operating Systems/linux/distributions)
2) Torx 10 And Torx 20 Screwdrivers - To Open XBOX
3) A Spare/Blank PC Hardrive (Can be anything from 10 GB to 10000 GB I think)
4) FTP Program (AceFTP, SmartFTP etc.)
5) A blank CD-R/W and A CD Burner
1. On your xbox's evox dashboard go to system utils and select backup. While your waiting for that to finish extract all files in xboxhdm 1.9 to your PC'S hard drive and open up the folder 'linux' in that folder is a folder called 'eeprom'. Once the backup is complete, on your PC run the desired FTP program and access your xbox. Go to E:\ backup_linux\ and download a file called 'eeprom.bin' to the xboxhdm\linux\eeprom folder of on your PC’s hard drive. Then go to the root of your xbox and download the full folders of C:\ and E:\ (You can use F:\ to if you want it) to your PC's hard drive to the xboxhdm\linux folder and overwrite the ones already there. Now in the root of xboxhdm is files named 'make-iso-win'. You must run make-iso-win and wait for it to finish once it has finished. Now burn the .iso which was created to a blank cd-r/w using nero or alcohol etc. When burning is finished shutdown pc.
2. Take out all other hard drives leaving a CD/DVD drive in and put in the hard drive you wish to make an xbox hard drive and set it to be the primary master. Boot up your PC and as it is loading press escape and set your PC to boot from CD. Now reset your PC and put the cd-r/w with the .iso you created on it, in the cd/dvd drive. You should be given a list of options. Choose Option 1 (by typing ‘1’) and press enter to boot VGA console with xbox-drive utilities (default). Type ‘xboxhd’ when it asks you for a login. Another list of options will show up, choose option 1 again (the one that says ‘Build a new Xbox HD from scratch’) and it will begin to format and write the partition table etc. If you put your C:\ and E:\ onto the CD then when it asks you about them type yes and when it asks you if you would like an F select yes, it is all pretty self explanatory. Now quit and reboot your PC. If this worked you now have a brand new nearly-usable xbox hard drive.
3) Now for locking the hard drive. When it boot from the cd agian, this time type ‘3’ and hit enter to boot linux with locking/unlocking utilities. Next, type in ‘lockhd -a’. It will now search for the eeprom on the CD and will automatically lock the hard drive. Now turn off the PC and take out the hard drive when it has finished locking.