How do you run make human in blender?
If you’ve downloaded it and installed it (assuming you are using windows) just load the blend file that is included with the installation. I would advise you to copy the base mesh file just in case you accidently mess it up. I don’t know if that’s a problem with pre-alpha 2.0 but it was known to be a problem with version 1.8.
You can append the script into your blend file by using the append command (shift F!), although from what I understand, MH is a very complex application so be careful of what you do.
MH pre-alpha 2.0 does not have alot of functionality as far as what will be capable (from what I understand) once the alpha and beta versions are released.
I’ve only played with it a bit, so I hope this will be a little helpful to you.