In this case you need to read directly in NDS.
There is a advansys exemple witch show you how to read user informations from GW with Formativ
PO is an object like the other, in NDS point of view 
Warning. If you could read, i think you couldn’t set something.
The only way i found to create GW external User directly from Formativ was to call a VB applet.
you say many, how much ?? 10,100, + ? Just professional curiosity 