So you wanna be a rock star? As long as your tastes lean toward Guns N’ Roses and the Clash, punk rock/ heavy metal karaoke may be the best way to get your headbanging on. At NYC club Arlene’s Grocery, weekly pseudoconcerts team wannabe Ozzys with a three piece backing band. ”If there’s an evolutionary scale of karaoke, then this is its highest form,” says filmmaker Sonny JL Aronson, 27, who chronicles the movement and its vocal regulars in ”Punk Rock/Heavy Metal Karaoke: The Movie.” Though Arlene’s has hosted the event for more than a year, this particular brand of sing along began in L.A. in 1996, aided by such rock luminaries as Devo’s Mark Mothersbaugh and the Minutemen’s Mike Watt. The flick — which soon hits the festival circuit — may inspire others to discover their inner Axl: ”It’s the ultimate way of fulfilling your fantasy of being a rock star.” Just don’t count on any groupies.