Is there any way to add a python script in the python section to categories like themes, import/export etc.?
Add something like this at the top of your script and put it in the folder with the others.
“”" Registration info for Blender menus:
Tooltip: ‘Create uv colour according to the angle of each edge.’
(scroll down to “Registering scripts:” )
(the section called “Scripts with BPY information” )
EDIT: just do what macouno said, and you’ll be fine