setting permissions for sg devices

[Debian User <shitse@xxxxxx>]

i'm searching for a way to set the permissions of the generic device that 
belongs to a cdrom device. it would be easy to set the permissions if i know 
the id of the device, but as i want to be able to change the ids without 
breaking the permissions i need a way to do that dynamically. does the devfsd 
have a way to do that, or would i need to create a script that changes the 
perms file everytime the bus changes?
thanks in advance
quitte