when installing python can i put it on an ext hd?
 

will i be able to use pip to install some mathlab components? or will the path be wrong?

pretty sure you can do this if you want

after installing the package use "pip show <package name>" and then make sure the location it shows is in your python path ($PYTHONPATH on unix). I wouldn't be surprised if it already is in the python path, even though you installed python on a secondary volume.

I think you would also need to add your python install location to your global path ($PATH on unix) in order for pip to find and run python