Assuming you are using a recent version of Poser (7+, and certainly 8+) you don't need to put the content in the application folder at all (Poser 6 with the DAZ humans, and some other items, does work better with at least those items in the application folder) - and if you are using Windows 7/8 or Vista then you definitely shouldn't put content there. If you already have the items installed for DS just point Poser to the same location (you want the folder that holds the Runtime folder). For new content, you need to merge the Runtime with the existing Runtime in whichever location you use - putting one Runtime inside another won't work; on Windows that's a matter of dragging the Runtime folder into the folder that holds the existing folder, but on a Mac it depends which version of the OS you are using as older ones can end up replacing rather than merging.