Conversion Hercules Prima S2

I have bought a Hercules Prima S2 today and would like to change or improve some things…I need a supplier for a flashing system and for a windshield (similar to Motoroller),for this I would like to convert the rear light into an LED light I need a TÜV permit for this or can I convert it into my own work?! can I use a flash or LED rear lamp of a motorade if necessary?