Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

We Salute You! (20 points): 5-Star all the songs on AC/DC LIVE: Rock Band Track Pack on any difficulty.
ALLLLLLLL Night Long! (30 points): Play through every song on AC/DC LIVE in one session.
Fifteen Million Fingers (30 points): Score 100% notes hit during a Guitar Solo on Expert.
Let There Be DRUMS! (25 points): Score 100% notes hit as a drummer on Expert.
Oi! Oi! Oi! (20 points): Score 100% notes hit as a bassist, upstrums only, on Expert.
Number One With a Bullet (25 points): Score a 100% rating as a vocalist on Expert.
Yeah, Yeah You Shook Me! (20 points): 5-Star "You Shook Me All Night Long" on Vocals or Guitar.
Done Dirt Cheap (20 points): 5-Star "Dirty Deeds Done Dirt Cheap" on Drums or Vocals.
Broke the Limit, We Hit the Town (20 points): 5-Star on "Thunderstruck" with Guitar or Drums.
Watch Me Explode! (20 points): 5-Star "T.N.T." on Bass or Drums.

Additionally, there are two secret achievements:

Back in Black (10 points): 4-Starred or better on a song after failing out and choosing "Retry".
For Those About to Rock... (10 points): Entered any mode with a four player band.