Categories

We are trying very hard to implement ITIL and SAS70 by making use of SD+. One area where I cannot seem to get a work around on is Change Control.

I separate requests using the categories into 3:
Incidents, Requests for Change and Requests for Service. (A generic example can be found at the bottom of this post)

The trouble is that only certain users should have permission to make Requests for Change but I cannot stop them from choosing categories.
Could there be a way to hide categories by permission if these could be set on a category?
Could this become a feature?
What would be a workaround for this?

Example of the methods I use for Categories.
Incidents
� Incident with App1
� Incident with App2
� Incident with PC1
� Incident with PC2 .... etc
Requests for Change
� RFC For Server1
� RFC for App1
� RFC for Security Permissions
� RFC for moving Computer Equipment .... etc
Requests for Service
� Assistance with App1
� Set up New Client
� Set up New Staff Member .... etc

Any request that falls under a Request for Change Category is then assigned to a queue system for change requests.