When i create an action in Documents, i cannot link it to a custom Python action.

This is from the document menu:

When i press one of the buttons in "Actions" i want a Python script to run, but i don't a find a way to do it.

When i try to congifure the actions like the image below:

There is no way to point to a python script when i create a new action:

Otherwise is there a way to add a button to a products template to run an action over an uploaded document?

Thanks in advance!