As far as the SDK goes, I would think TunerAvailable(Boolean), GetCurrentChannel, SetCurrentChannel, and SetScheduler should do it. Additional commands to get a list of available channels, and/or information about the tuner might be nice. Thanks for listening Yao.
Also, and I know this isn't the proper forum for this (sorry), I wrote a media library a while back, and I kept a variable all plugins could access call Command. It was a basic form of scripting that allowed communication back and forth. Anytime a plugin (or the main mod) did something, it changed the variable to report what it just did. This allowed other plugins to respond. You could also send commands (Library.AddFile fileName) to the library or other plugins. As long as the plugin knew the command you sent, it could do anything. Just a suggestion for extending the capabilities of the SDK.
-Tano