The Good News.  It is easily done.

 

Import the obj into Poser.

Go to Props.

Go to the folder (or create it with the create folder button)

Click on the + box

The OBJ is now a prop in your props folder.

 

The bad news.......

 

Poser puts the obj information into the pp2 file instead of referencing the original obj file.  In addition, the prop will reference the textures at their currrent location - it doesn't move them into a folder in the textures folder.

 

The good news......

Daz Studio has a 3rd party addon called obj2pp2 and as I understand it, it will take your obj file and make a pp2 file that poser can read without dumping the obj information into the pp2 file.  It can be gotten here:

http://jwas3d.com/

The bad news......

I don't know if there is something like it for Poser.  - I would think that it would be easy for one of the python folks to develop something.  All that needs to be done is strip out the obj information and replace it with a reference to the obj file.  Fixing the textures would simply consist of converting the absolute references in the pp2 file to a relative reference back to the texture file location.

At the moment, I am stuck with hand-jamming it. 

 

But I have confidence that the PoserPython community could come up with a simple fix.  It has been done for Daz Studio - how hard could it really be?