Ok, I've just gone back and looked at the DSON installers and realised they are applications. I've just installed into my old poser pro 2014 and the installation went fine. You should just be able to double click on the DSON installer without it being installed in poser and it will run and ask where you want to install it. Have you got this far? (Sorry for the confusion it's been some time since I installed this.) You can use the browse function to select the correct folder if it's different from that suggested. (For example when I ran it it suggested poser 2012, so your version might suggest poser 9.)