Before installing any newer versions since version 2.5, you must partialy uninstall
the old versions. (this steps are only for neodex .77 to 2.41 unistallation)

Steps:
before you do anything run the NeoDexMenuUnistaller.ms 
    (only unregister if u are sure u didn't add NeoDex's menu somewhere else manually)
1st close 3dsmax/gmax
2nd Go to 3ds max's/gmax's installation directory.
-- (note if you don't know it, open the listener in 3dsmax and type "getDir #maxRoot" without "
3rd enter 3dsmax/plugins (or gmax/plugins) and delete every plugin that starts with "NeoDex"
-- (there are more plugins, but these are kept in new versions)
4th go back to your 3ds max's/gmax's installation directory.
5th go to ui/macroscripts/ in your 3ds max's/gmax's install directory.
6th delete the file "Macro_NeoDex.mcr"
You are done now, you can install the new version.
There's an extra step if you really want to eradicate the old version

Optional Extra Step to delete it completely:

3dsmax 2008(or 8?) and up:
    - in windows search type "AppData"
    - access that folder and go to Local/Autodesk/3dsmax/(ur version)/enu/ui/usermacros
    - delete any files that start with MDL_Kit
    
 gmax and 3ds max 8(or 9?) and down:
    - just go to (gmax or 3dsmax)/ui/macroscripts
    - delete any files that start with MDL_Kit
    
Now you should be safe from the evilness of the old version messing with the new one 
    (the extra step is not really necessary but frees u from any crap left behind).
IMPORTANT: You won't have to do this again if a new version comes out.

Now install NeoDex as in the other README