Before you can say “Beetlejuice” three times, you might wonder how a high-stakes Broadway-bound musical will render the low-key effects and unpretentious style of Tim Burton’s 1988 cult-favorite haunted-house movie. “It’s the first film where you really see his visual imprint,” says director Alex Timbers, in Washington getting “Beetlejuice” on its feet following his premiere of the new $28 million “Moulin Rouge” musical in Boston. “Do you try to make your own thing, or run to