I'll just paste the head-drop tut I wrote for Slof. You can do it with your piercings just the same. After you export them as FO3 meshes (make sure to delete the skeleton and vertex groups), use NifSkope's Export as OBJ feature with the NiTriStrips selected.
Select the head and Import the skeleton with 'Import Skeleton Only + Parent Selected'
http://tes.kikaimegami.com/tutorials/droppinghead/01.jpg
Select the skeleton.
http://tes.kikaimegami.com/tutorials/droppinghead/02.jpg
Hit Ctrl+Tab to go into pose mode
http://tes.kikaimegami.com/tutorials/droppinghead/03.jpg
Or, alternately you can use the mode dropdown
http://tes.kikaimegami.com/tutorials/droppinghead/04.jpg
Select the Head bone
http://tes.kikaimegami.com/tutorials/droppinghead/05.jpg
Shift+s Cursor to Selection
http://tes.kikaimegami.com/tutorials/droppinghead/06.jpg
http://tes.kikaimegami.com/tutorials/droppinghead/07.jpg
Select the head and click 'Center Cursor'
http://tes.kikaimegami.com/tutorials/droppinghead/08.jpg
Select the skeleton again
http://tes.kikaimegami.com/tutorials/droppinghead/09.jpg
Ctrl+tab or use the dropdown to go back to Object Mode
http://tes.kikaimegami.com/tutorials/droppinghead/10.jpg
With the skeleton selected, shift+s cursor to selection.
http://tes.kikaimegami.com/tutorials/droppinghead/11.jpg
Select the head, shift+s Selection to cursor
http://tes.kikaimegami.com/tutorials/droppinghead/12.jpg
There you have it!
http://tes.kikaimegami.com/tutorials/droppinghead/13.jpg
You can delete the skeleton now if you want.
Also, here's a short explaination of how to do the Conformulator bit that I wrote for Zealotlee
1. Download and install The Conformulator: http://www.tesnexus.com/downloads/file.php?id=9360
2. Unpack the Meshes BSA (you can use FOMM to do this). Put it wherever you like. I've got mine in a Fallout3 Files directory.
3. Open your mesh and select the NiTriStrips block, then right-click it and go to Transform, Apply.
4. With the block still selected, go to File, Export, Export .OBJ then navigate to the directory where your mesh is saved and name the obj the same as the mesh, so in this instance, it would be pithhelmet.obj
5. Run The Conformulator (it'll add it to your start menu, or it should auto-install to C:\Program Files\The Conformulator\
6. In the Conformulator, the Head file is \data\meshes\characters\head\headhuman.tri from your extracted BSA; the Hair File is your exported OBJ
7. Quality should be Nearest Face and Tri File set to None, don't bother with the Falloff stuff.
8. Click Conformulate and it'll let you know when the file has been created. It'll place it and name it exactly what it needs to be in order to work.
9. Now the Update Facegen Model Availability should work and it should show up ingame like my screenshot.
EDIT: Not all of these steps will be relevant for you, but you seem to know enough to understand what bits you do. If it's still a bit confusing, I'll piddle it to fit your situation.