Winglit our company is third party (not an Operator) and it is not possible for us working based on "tag" system.
Being third party there is no procedure. If an operator removes an engine they commonly swap gearbox components from the U/S engine to the new/overhauled one. The airline has it's procedures for parts tracking, foreign or domestic it is their responsibility.
Being third party you should be able to go to your CAA (assuming you have some sort of repair station license) and create a removed serviceable tag approved to add to your operating manual. It is though only for your purpose of identifying parts at your facility and showing the airline/operator that you have parts control.
Simple answer is NO, you can not make a part serviceable unless you are licensed to overhaul that part.