Is the python script running on a different Mac? If it is on the same Mac, then you can have Indigo execute it from the Execute Script action, either embedded in the edit field of that action panel or as an external file. You can also use the
indigohost process to execute the script. There are
some examples here. Note indigohost is really an alias to a binary inside the IndigoPluginHost.app package. Near the top of that wiki page it shows how to create the alias in your .bashrc file so it can be accessed more easily.
All the above techniques automagically make available the python indigo module. It is actually embedded inside the indigohost. It handles the communication with the IndigoServer and provides all the indigo API calls. Currently the only way to get access to that module is by executing the script from Indigo or via the indigohost process. That is, there is no way to import the indigo module into a python script that isn't running inside the indigohost. If that is a requirement then using the much more limited RESTful API is a good approach.