You will need to defining a new language, but the existing definitions for
Python can help.
I have never defined a Notepad++ language, but here is what I know :
Unfortunately, built-in and user-defined languages are defined in two
separate locations and by two different mechanisms.
In both cases, they are defined inside XML files.
You will need to understand XML a little if you wish to appropriate parts
from the existing definition for python, but you will build your language
by using the menu command Language -> Define your language.
Built-in definitions are found in the file
C:\Program Files (x86)\Notepad++\langs.model.xml.
You can search this file for
python and find this very simple-minded definition :
<Language name="python" ext="py pyw" commentLine="#">
<Keywords name="instre1">and as assert break class continue def del elif else except exec False finally for from global if import in is lambda None not or pass print raise return triple True try while with yield</Keywords>
The above definition is only good for extracting from it the list of all the
python keywords, which you can then break into groups.
More python definitions are to be found in more files, but they are not
worth the effort of appropriating them.
Now go into the Define your language menu.
This dialog allows you to entirely define the python language.
Your first step should be the button "Create new...", enter a name
such as "Python mine", and continue from there.
You will also need to go into the menu of Settings -> Style Configurator,
click on "Python" and delete its file extensions in the "Default ext.:" box,
so as to revoke these extensions from the built-in python language.
Add these file-extensions to your new language definition.
For better understanding the Define your language dialog, here are some references :