I have searched a bit but didn't found anything. In the (unfortunately) gone painting subforum people mentioned that they disassembled the wings of a TIE-FIghter in order to paint the model more easily, and then reattached them again. I do not want to destroy the model, so anyone any advance on how the model sits together, and where one has to pull?

Having just repainted a bunch of TIEs, there's no need to dismantle them at all.

Just take off the base and pegs, shove a cocktail stick in the mount, mask the mount and off you go.

The only reason you might want to pull the wing off is if you're planning on a complex design on the inside surface, and even then it's really fairly accessible.

Try using a super glue debonder. If you cut part of the eye off of a sewing needle you can use it to feed a drop of debonder into the wing join. Be very careful cutting the eye. Needles are hardened steel. That cut end will take off when cut. A method to soften it requires you to heat the medal till red hot then letting it air cool. Use eye protection regardless.