I had the same issue a few weeks ago. I solves this issue with a program called killproc. It works on CE6.0, don't know if this works on WM6.5.
I created a autorun package, as startupcommand a cmd file. The CMD file killed the proccess and installs my cab file.
wceload.exe /noui /noaskdest /nodelete mycabfile.cab
killproc can be downloaded here
killproc.zip 1.1 K
Thank you so much, It Works!!!