What Does "install-me" And "pre-install Me" Do While Ap's Stuff Is Installed?

erm

 

You would have to give us a clue as to where you have seen this.
It is not in every add-on

 

Looking at a Reskin I installed today the "instalme" is usually a installme.bat file that copied the various files required for a reskin to work

 

I think it copies the Geo files from the original model into the subfolders of the new variations.