Just double click the phi builder icon in Explorer, Its a stand alone, it does not run inside of Poser.

If you want it to run in Poser Pro you'll need a dummy Poser.exe file. Create a new text file in your Poser Pro folder and rename it "Poser.exe"

Also whilst I think of it, it is best not to call a body part "body" and definitly not "BODY". Poser uses those keywords, and I know a number of scripts do also.