“Only in New York”: that’s the kind of vibe that 54 Below, the recently opened cabaret in the basement of Studio 54 that calls itself “Broadway’s Nightclub,” strives to create. And my first time there tonight, it worked. The headliner was Jenifer Lewis, a mouthy comic singer and performer who’s toiled in New York theater, spent five years on a TV show called Strong Medicine, and once toured as backup singer for Bette Midler. Along the way, she acquired an adopted daughter and became a poster girl for bipolar disorder. All of that figures in her act, much of it special material created for her by her musical director, Marc Shaiman, who’s a gifted composer and arranger but more than anything else is kind of a great diva wrangler (Bette being his first and foremost diva). He’s a superb accompanist, in that he’s a nimble piano player but also strikes the perfect balance on stage between invisible partner and sweet all-purpose straight man. Well, straight man who’s as gay as they come. The original material will not be covered by other singers any time soon — “Black Don’t Crack,” about how female celebrities of a certain age don’t have to submit to Botox-face the way their white counterparts do, and “Sang Bitch,” a tribute to other beloved performers. The cover songs are surprising and, I have to say, very well-sung. Imagine Kiki and Herb with less onstage drinking and better pitch. The show, directed by Scott Wittman (Shaiman’s partner in crime and life), runs through Saturday July 28.