Ok .. I just made a little addon to help with this :-)

It's only for Poser 9 / PP2012 with SR3

If you click on 'Stick' then the addon makes a note of the currently selected actor and then won't let Poser change the selection to anything else.

Click on 'Unstick' to go back to normal operation where you can select other actors.

Maybe useful for stuff other than just the morph tool?

Free stuff @ https://poser.cobrablade.net/