In an interview with Knac.com (read the full interview here) co-creator Brendon Small says: "When the show was first being conceived of by Tommy and myself it was like “yeah, if we want to go out on tour we could do something like Gorillaz” and then all the fans started writing in and saying “dude, you should go on tour but do it like Gorillaz.” Everyone was on the same page, and I was like “well, if we do it it should be cool, it should be funny and we should have a pretty good band playing. And it shouldn’t be about the actual band playing onstage, we should hear the band but not see them.” So we might be backlit, nearly out of sight or something, and we’ll have like an extended episode of the show playing on a huge screen that we'll play along to. So it will be a mix of music, and the characters telling little stories throughout, have these soundoff points where you get to laugh. The musicianship should be incredibly good, and it should take itself seriously enough to do it right. So that’s what we’re doing now."
More information on Dethklok and Metalocalypse on Wikipedia here