Welcome to the club. It is a rather complex subject. The basic idea is:

Import V4 in the scene
From the FST menu select "Copy from selected figure"
Right click in the geometry pane and select import geometry. Import your OBJ
Drag-and-drop your geometry in the imported hierarchy, the list of bones imported from V4. Use the hip bone as your root.
Remove all the IKs.
Remove the bones that are not used. For example finger, if you are making a pair of pants.
Rename the hierarchy label to remove the original V4 label.
With V4 selected click on the FST tool menu and select "Paste into figure". V4 will be replaced with your outfit rigged properly.

Tada!

Forum: DAZ|Studio

Subject: Daz Studio and Figure Setup Tool