In fact here is one now for people to test for me, its a work in progress for the nations kit pack... as far as i know this is what you need to do. Save the xml file into the following folder:
My Documents\Sports Interactive\Football Manager 2012\editor data
Then start a new game in FM2012 (not a saved game) using the 12.2.0 database (or whatever the latest one is - dont use default), if you have put the xml file in the right place, on the screen where you choose the database to use it will say Editor data files: 1 enabled (if you only have the one in that folder).
Then click ok.... dont make any changes to the existing nations europe kit pack config....
See if the all teams up to bulgaria show up... thats as far as i have got so far.. so thats Albania, andorra, armenia, austria, azerbaijan, belarus, belgium, bosnia & bulgaria. Oh and England too.