title: What are the steps taken with pip install in python
body: <p>I am trying to install a package via pip, but there were missing files from the zip file. So I copy the files and then compile with gcc. But now I cannot continue with the installation by calling pip install because it sees a pre-existing directory and will not proceed.
  This is with pip version 1.5.6, but I thought that with earlier versions of pip that it was less fussy about this. 
  What are the remaining steps to complete the package installation?</p>