Navigate to the System Update (X) drive, and create 2 folders, one labeled "A" and one "B"

Extract all of the files from OSU1, and copy everything in $SystemUpdate, except for "updater.xvd"

Paste these files in the folders "A" and "B" that you created.

Copy "updater.xvd" from $SystemUpdate and paste it in the root of System Update (X)

Note that you will need to download the bootanim.dat and store it in folders "A" and "B" as well. There are two different versions you can download one for OG / S or the X. Without the file the Xbox will boot with a black screen to the menu and not the boot logo.