in Poser 6, the library section on the right side of the interface window, click on the FOLDER looking icon near the top of the list...it will have an upward pointing arrow unless you are to the main folder.

The P6 folder will then have a red dot next to it if that is your current runtime you are using.

Then, at the bottom of the list, you will see a + plus sign. Click it.

You can then browse to your P5 location on your hard drive...choose Poser 5 and you will then have it listed in your P6 library

Humankind has not woven the web of life. We are but one thread within it.
Whatever we do to the web, we do to ourselves. All things are bound together.
All things connect......Chief Seattle, 1854