hello! I wanted a certain pak file to work on any version of simutrans. would set up the game for that to happen?
You can't and I see no reason to do so. First of, you would need to find out which objects exist since the very first version, then you would need to find out which parameters for this object exist since this same version and then you would need to find the makeobj for that version.
The first versions of Simutrans didn't support modding through pak files as far as I have understood. But if you restrict your definition of "any" to more recent versions of Simutrans, An_dz did provide the way to do it. If no suitable version of makeobj can be found in the wild, you may have to compile it yourself from SVN. Of course, an old pak file won't support features added in later versions of Simutrans. Upon loading, Simutrans will use default values for missing parameters, which may or may not be ideal. There is also the possibility that something is broken in the loading of old pak files, as that isn't as thorougly tested as the loading of newer pak files.