Script to enable internet sharing over AirPort

My friend shares his internet connection with his roommates through his AirPort card, but sharing is disabled whenever the computer goes to sleep. He still wants his computer to go to sleep, and doesn’t mind re-enabling Sharing everytime he wakes it up, but I thought a script would help.

I’ve gotten as far as

tell application "System Preferences"
	set current pane to pane "Sharing"
end tell

but I don’t know how to select the “Internet” tab, or where to go from there. Any suggestions? Also, where can you look up this information?