In one word.....No
The only way you could work this,:-
You set up the file in X4 or X5 ( geometry only ), & "Save as" X4
He programs the job in X4, you could open, ammend & post that file in X4 . And he would still be able to do stuff with that file
Once you overwrite that file with a later verion, the toolpath ops are only available to the same ( or later ) versions. He could open ( without toolpaths only ) if he saves, then those toolpaths are gone from that file for good.
Best senario would be for you to download & install X4 - you both work at the same version level
( you can run both versions on the same machine )