Someone else will have to break it down into smaller steps, that is as simple as I can explain it.
It really is just that.

A MIpose can be from a face pose = fc2. or a pose pose = pz2.
The face pose comes from Poser with all you need for a head morph. It will usually want to have eye placement data in it, but that involves some cut/paste and that seems to terrify most users. Dan Wilmes' CR2Edit 6 will do that for you, if it does. I wouldn't be surprised if it would not copy over the morph too.

Spawn Morph Target
just means combine all the morphs in this group and make a new morph from the combination.
The verb does remind one of fish reproducing, but I can't think of a better verb, so Larry did about as well as could be done with the name of the function.
If you want to save the new morph, you have to save the CR2.

After you Spawn a morph, the steps are the same as they are when you apply an outside morph - you have to name it.
What you type in place of 'shape1' goes into two places in the new morph
its channel name - the first line - starts with: targetGeom
The dial name - Name --

You can then change the Name - dial name - hierarchy editor - or in the grey parameter window
The targetGeom part is out of reach after this single shot - you can text edit it , but not inside Poser.

Naming the morph with a channel name that is in V3

Poser 4 will not let you have two morphs in a group with the same channel name, it deletes all but one, - WHEN you reopen the CR2. I am not sure, but I think it saves the last one in.
Poser 5 makes the name slightly different - adds a number or something. So the trick of naming the Spawned morph as one of the DAZ community slots probably will not work without some text editing - but MM4 will let you type a new name if you go into properties for the morph. It is just a real slow text editor and cumbersome at it to boot.

The rules are simple:
You want the whole morph in a pose file.
You don't want anything else dealing with other morphs in there.
You want the targetGeom NAME to match a targetGeom NAME that is in the CR2 you use it on.

The fine points are:
you can set and lock the eyes.
you can scale - usually done with body morphs, not just head.
you can have a texture assignment in there - also usually done with a whole body character, not a face, but you can do a complete MATpose in a face MIpose if you have a mind to.