Here I use the Enthought Canopy distribution of python. I assume the steps would be similar if you used anaconda or "regular" python that comes with your Mac.
- Open the editor --> Tools (top menu bar) --> Canopy Terminal
- Type in "sudo pip install nipype" (you should already have pip installed. I forgot how I did this, will edit once I remember)
- In the "Python" window of the editor, type in "import nipype"
- You are likely to get an error saying, "no module named XXX"
- Go back to the terminal and type "sudo pip install XXX", where XXX is the name of the module that is missing
- Keep doing this until you successfully import nipype.