Found the answer by myself:
I used this tutorial:
QUOTE
How to patch an xex file with an xexp patch file.
Updates to games and system files are provided over xbox live in the form of
patch files. These updates are stored inside package files in the Cache folder
on you hard drive. A system update usually has "SU" as part of the filename,
and a title update (game update) usually has a "TU" as part of the filename.
A patch file will only work when used with an untouched version of the original
xex file it was created for. When you have the original xex file and the patch
file you want to use with it, do the following to create the updated xex:
xextool -p patch.xexp -o output.xex input.xex
Note: A retail xex requires a retail patch file, a devkit xex requires a devkit
patch file. If an xex has been converted from a retail to a devkit xex, you need
to use the retail patch file with the original retail xex, then convert the
resultant xex file into a devkit xex file.
so:
1. Re-extract the corresponding xex file from the Image/Disc (as it needs to be a retail xex). In the case of Modern Warfare 2, it'll be default.xex and default_mp.xex.
2. Extract the xexp files from the Title Update (I used le-Fluffie).
3. copy the xexp files for these into the same folder as xex tool.
4. Run the following commands:
xextool -p default.xexp -o default.xex.patched default.xex
do the same with the default_mp.xex:
xextool -p default_mp.xexp -o default_mp.xex.patched default_mp.xex
5. Save your original xex / xexp files elsewhere and remove the .patched extensions from the two created files.
6. Run X360GameHack and point it to this folder. It should report that 2 files have been patched.
7. Copy back to your game folder and (according to the document) it should work.
and additional I extracted the content of Root\disc001\Media\cars\driver from the update package and replaced the files in the coresponding folders of the game on my usb drive.
Then I removed all the files from my \cache Folder on my 360disc.
The game starts now propperly from usb and my savegame works !