The stage/gate workflow is not configurable in the manner you describe.
The basic concept is to standardize projects into a common pattern. While some templates can be used to reduce the number of stages/gates that must be managed in a given project the method for passing through gates is common.
In 6.1 we did add extensible features to the project workflow and save. These are similar to what we have in GSM. If you can standardize the procedure you may be able to write a customization using the workflow extension.