1) Insert usb to xbox, go to memory and configure the flash drive to work with xbox.
2) On your pc create a folder called "Content"
3) Inside the Cotent folder, create a folder called "0000000000000000" (it should be 16 zeros)
4) Look in you extracted xexmenu folder for a folder name "LIVE" (for xexmenu live)
5) Within the "LIVE" folder there should be a folder "C0DE9999"
4) Copy and paste "C0DE9999" in the "0000000000000000" folder
5) Download USB Xplorer (google it)
6)Insert the flash drive that was configured by your xbox, and open the drive (file ->open) via Xplorer
7) You should see a cache partition and data, click on the data partion
8) right click in the open space and hit "inject folder", now select the "Content" folder
You should be good now.
note: you may need to download xexmenu live not xexmenu (not sure if they are combined or not now)