You can put these folders containing runtimes whereever you like. Here's a screen cap.. they don't need to be ordered.  Once you ahve a lot of them you'll need a way of loading them all automatically as one at a time is slow. but once they are loaded in poser, then poser remembers them, unless you move them somewhere else.

Love esther

Ps here's how it looks on my mac

MY ONLINE COMIC IS NOW LIVE

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