An obj file can only be used as a morph if it uses the same mesh as the actor in the figure you want to morph. In other words to morph V4's bead, your obj needs to be a morphed version of the V4 head, with the same winding order and the same vertex count.

Assuming those conditions are met, there are a number of methods to to package the morph in a pz2 file. Here is one method.

Download and install svdl's "SpawnCharacterP6 update" Python script.

In Poser, Load V4, turn off IK, zero the figure in the Joint Editor. Load the obj file into V4's head as a morph target (Object > Load Morph Target). Express the morph at a value of 1.0, make sure no other morphs are affecting the figure.

Run the SpawnCharacterP6 script. Click the various fields from the top down, filling in the the relevant information as you go. The first field is "Enter morph name", this is the name that will appear above the morph dial. The second field "Select a channel" lets you choose which PBMCC channel the morph will be injected into. Clicking the third field "Save INJ REM in" lets you chose where to save the pose files. The other fields can be left at their default. Click the "Generate" button. The script will run for a while, then your INJ and REM files will be saved to the folder you specified.

An alternative is to use the stand-alone "Pozers Little Helper" application to create the INJ and REM files. It is available from "Winscape 2000".

I'm sure the using Poser File Editor, as mentioned by MatCreator, would work just as well as the methods above.