VCS tries to offline the resource by stopping the service. If the service hangs in the "Stopping" state then this indicates an issue with the service. i.e if you tried to stop the service in Windows services and it hangs in the stopping state then there is no "force stop" in windows services and you would have to kill the process as you are having to do with VCS.
You can create a resnotoff event trigger (see "resnotoff event trigger" in the VCS admin guide) which would involve writing a batch script or perl script to kill the process and the trigger is invoked when a resource can't offline. There is a sample resnotoff in \program files\VERITAS\cluster server\bin\Sample_Triggers which shuts down server if resource cannot be offlined, but you don't have to use this code (which is how the admin guide reads), you can replace the code with whatever you want. The resnotoff script is passed the system name and the resource name so you would have to determine what process to kill from the resource name.
But you rbest course of action is to find out why your service does not stop properly.
Mike
