Here's what you need to do:
1 - I'm assuming you're using the default content location (DazStudioContent).  If not, let me know so we can make sure the V4.2EZ installed with D|S isn't messing up your full V4.2
2 - Install V4.2 and the V4.2 Base Powerloader, if you haven't already.
3 - Install Morphs++.  When it finishes it will ask if you want to Initialize -- click Yes and make sure it said it Initialized successfully.
4 - Install the Morphs++ Powerloader.

Now, when you double-click on V4.2 in the Content tab, the Powerloader will appear and let you check off which morphs you want to include.  Make sure Base and Morphs++ are checked.  Now V4.2 will load with morphs++ included.