Documentation for Developing Multi-site Extensions?

Does anyone know if there is any documentation or tutorials that explain how to create a MSM aware extension? I can’t seem to find any details on how to to do this. I need to create an extension for EE 1.6.9 but I need it to be limited to specific sites. One question I have is:

• Can you use the abstracted settings and still have a MSM aware extension?
• If yes, how?
• If no, then I assume you need to create custom settings_form() and settings_save() methods?

Any help is appreciated.