Without further ado, here are the Ed Anderson 2622 and 2623-4 transformer Eagle 5.11 files from the ClassicAPI transformer collection:
http://www.evolutionarytheory.com/downloads/Eagle/V5/ClassicAPI.lbr
In hindsight I probably should have called this EdAnderson.lbr, sorry Ed!
Regardless, so that people know the back conversions are indeed possible, after a LOT of searching here is how you can do it (for libraries, anyway).
1.) Open the library in v6
2.) Select File->Export->Script
3.) Select your destination and export as a *.scr
4.) Close v6
5.) Open v5
6.) Create a new library and name it the same name as the old one (assuming you want a direct conversion of the lib, obvious don't overwrite the v6 one, just chuck it in a v5 subfolder or something).
7.) Open the new v5 empty lib
8.) Choose File->Script (which, weirdly, executes the script, even though one would assume it should be called "Execute Script"....)
9.) Skip over the inevitable warning messages
10.) Eagle continues even past the warning messages, which, IMO, is the mark of good programming, as it tries to get as far as it can
In my particular case, this was enough to get it correct in v5.
enjoy!