This is a license based feature.
Licenses can be purchased using the TRIAX website: HowTo purchase a license
When the feature is enabled, it allows you to modify the output PID's.
Note: Changing the service-ID (SID) does not require a license.
1. Access the headend.
2. Select "setup" for the output you wish to modify.
3. Select "services"
4. When the license based feature is active, the output PIDs can changed/modified.