It would be important having an Extension when, if , using an external library that is taking access to the

    >AppData>Roaming>Poser??>Nr.??>LibraryPrefs.xml file

giving the option in that document to add and remove runtimes into the specific Poser versions

by changing the lines after the <LibraryPreferences in the txt any external runtime could be added through a specific external Library application.

It also can be done manually but for most it is difficult to understand how the lines need to be added.