just copy the runtmes, not your actual other files to do with the running of poser eg .exe or your actual poser application etc
Gone are the days of needing softrabbit etc that makers of content still refer to.  It's not needed for modern versions of poser.  Poser reads the PC path names and mac path names, pz2s etc without problem interchangeably.

One thing to be careful of, which is the major difference when using mac compared to PC with poser folders.  remember on a pc if you drop a folder say, called runtime into another folder called runtime it will merge the contents of the two runtimes.
On a mac it is different. If you do that you will replace all the folders inside runtime with the folders of your new runtime.
If you want to merge to folders rather than replace every subfolder and file, then you need to use Kaveman's utility called ditto, which I use every single day of my poser life for merging folders together.
But yes, the runtimes work exactly the same, no need to alter anything - just copy your folders across, and merge rather than replace if you want to keep some other stuff that you had previously on the mac version.
Love esther

MY ONLINE COMIC IS NOW LIVE

I aim to update it about once a month.  Oh, and it's free!