I can install V4 and A4 into external rntimes no issues.

What I do is create a fake poser.exe file, but first creating a txt file then renaming it poser.exe and keeping it in a different folder than from my real Poser folder ( warning - if you ever copy that back into your Poser folder, you're doomed ).

Or you can copy the poser.exe file into the external folder of your choice ( probably better to do this).

I then run the V4 then A4 installers, telling them to look for the poser.exe file in that other folder.

Eternal Hobbyist