Makehuman and the mhx2 skeleton are a good base for posing a character. But we all noticed, that there are some poses which have problems. I will now change one of my characters to work with corrective shape-keys. The normal bones of the skeleton will also manipulate the shape-keys via driver. I must admit, that this topic is rather new for me, but the results justified the work so far.
I started by watching this tutorial, it is rather short and simple to understand:
https://www.youtube.com/watch?v=wUs04SGUnVI
First objects to manipulate are eyelids and eyelashes. Have you ever tried to close the eyes and compare this with reality? The eyes did not really close, you get weird effects (picture on the left side):
It should look like this:
So we need four shape-keys, two for the eyelids and two for the eyelashes which should be connected to the orbicularis03 bones of the skeleton. We have to create basis and two additional shape-keys for the skin and the eyelashes. To edit the vertices in the final state, select the marked buttons of the armature-modifier of the eyelashes and the skin. Then pose the bone in final position and correct the vertices with the corresponding shape-key selected.
To add the driver you must use the right mouse button over the input field (took me some time to figure that out ) and add the driver (to be created later manually). The driver is setup in the animation screen.
These are only some hints, together with the video-tutorial above you should now be able to do the same. Just a hint: mirroring the shape-keys may fail, because your character may not be fully symmetric.
Here is a very short video (best to be played in slow-motion) to see the bones + shape-keys working:
I will add a some information for other shape-keys in future.