You can use the GUI-version of GP4Tweaker together with CSM by just changing one single file in CSM.
Go to the installation folder of CSM and open folder settings (standard would be C:\Program Files (x86)\ZaZ GP4 Tools\Settings\). You'll find the file "Carset Manager.ini" along with a few other files. Open this one and look for the following line:
"OriginalEXECheck=1"
Change this to "OriginalEXECheck=0" and you're good to go. CSM will give you a warning but it should work well, I never encountered any problem.
Oh, obviously I'll not take responsibility for anything that will happen when you change the line ^^
Whether it's possible directly for CSM, don't know.
Greetings
Sebastian