If you can modify the IPTV stalker client to be compliant i am sure there are many users who feel the same way as you and prefer that client. you can let me know if/when you have a working build and i can have them check to ensure it is compliant.
I don't think you need the source as there are no compiled dll's, etc you should just need to EDIT the Python scripts (addon.py, config.py and server.py) to add a Username/Password request.
Whereis the source code for that addon ?
I would love to try my hand and get immersed in this world of yours...