modify request header   

Hi
I Have a problem with a mobile browser [samsung 770] ,in ACCEPT header 
request is write *.drm i need to push to mobile *.3gp file not a DRM file,my 
IIS return HTTP 406 , two questions.
1. ISAPI filter can modify the ACCEPT header ?
2. what is best starting point to write such kind a filter?

Thanks

date: Sat, 28 Jun 2008 06:46:00 -0700   author:   zemp xp