Hi,
I am also having an issue getting WCCP v2 on 6807 in VSS working with websence, which i have been unable to get it working yet, however the service identifiers i can answer, websense use the following service id depending on the traffic you want to redirect

and they attach i believe as followed, you also need to enable at the global level
ip wccp 0
ip wccp 70
interface GigabitEthernet0/1
ip wccp web-cache redirect out
ip wccp 0 redirect out
ip wccp 70 redirect out
However beyond that i can not help, so if you manage to get it working please update me.
Thanks