New York ? It is the steamiest June weekend in Manhattan in years, with temperatures in Central Park skulking into the mid-90s. Will Smith, of course, breaks no sweat.

And forget Mama’s advice about light colors in the heat: Smith’s wearing head-to-toe black as in “Men In” broken up only by the big gold interlocking G’s on the buckle of a Gucci belt that costs more than you make in a month, and by a pair of silver dog tags.

“One has the name of my boys,” said Smith, fingering the necklace, “and the other one’s my girls. Jada gave it to me on Father’s Day last year.”

The boys would be Trey Willard Smith III, age 10, born to Smith and his first wife, Sheree Zampino and Jaden, almost 4. The girls would be his daughter Willow, 2, and Smith’s wife, Jada Pinkett-Smith, mother of Jaden and Willow.

Willow and Jaden had to stay home, but Trey was allowed to accompany the Smiths to a screening of “MIIB: Men in Black II” a few days earlier, and Smith figured Trey’s glowing review was the only one that mattered.

“If you can impress your own kid,” Smith said, “the rest is pretty much gravy.”

To some, it may seem like the last decade of Smith’s life has been gravy, and with “MIIB: Men in Black II,” which opens Wednesday for the Fourth of July holiday weekend, he looks to have fallen into the gravy bowl.

Truly payday

Though 1997’s “Men in Black” made more than $600 million worldwide, standing as Columbia Pictures’ most successful film until “Spider-Man,” Smith reportedly was paid about $5 million and had none of the all-important back end, a percentage of the eventual gross.

For the sequel, Smith, 33, is rumored to get $20 million still a few bucks shy of the $25 million per picture now being commanded by Mel Gibson and Tom Cruise, but director Barry Sonnenfeld says Smith’s back-end deal could amount to even more than the actual paycheck.

“Basically, to make the deal, Steven had to give up some of his slice,” says Sonnenfeld of the film’s executive producer, Steven Spielberg. “There’s still the potential for everybody to make a lot of money unless, of course, I screwed up, which is always possible.”

Even as Smith attempted to make the case that making the sequel was never about the payday, he displayed a bigger grin than usual, which means it threatened to crowd the furniture out of his Manhattan hotel suite. Grabbing some pillows from another couch and stretching out in a pose not dissimilar to the one affected for the cover of his brand-new CD “Born to Reign,” Smith maintained that his doing the sequel was always dependent on a “script that could stand with the first one and being able to get everyone together in one place at one time.”

Teamwork is key

“We’re a team,” said Smith of himself and co-star Tommy Lee Jones, who play secret agent alien-hunters, and Sonnenfeld. “And with us all pretty successful, it’s hard to pin us all down at the same time. I think we’re pretty lucky, really, that there seemed to always be a demand for a sequel, you know? Even a lot of good movies, when the sequel doesn’t come out pretty quick, you kind of forget about it. The fact that everybody still wanted this to happen made us want to make it happen.”

For his part, Sonnenfeld said he would have never done it without Smith, “because him and Tommy are the guys.” To prove the point, the film begins with Smith’s character, Agent Jay, paired with a new partner. Jones’ Agent Kay, you may remember, left the agency at the end of the first film, his memory of all things alien erased, or neuralized.

To save the planet yet again, this time from an evil invader disguised as a Victoria’s Secret model (Lara Flynn Boyle), Jay has to unneuralize Kay, now employed as a small-town postal clerk.

“There’s just something about me and Tommy Lee together that clicks, and it goes beyond the obvious thing of us being so different,” said Smith, in the understatement of at least a century. While Smith is so endearingly playful he could probably turn a Taliban member on to hip-hop, Jones is known for being professionally all business and personally disagreeable.

Smith said that Jones simply had no use for the glad-hand side of showbiz and that he was actually “a very funny dude.” As evidence, he pointed to a scene in “MIIB” that he said “I know everybody is going to give me the credit for.” It has rapper Biz Markie playing an angry alien and Agent Kay communicating with him by beatboxing the human-turntable-throat vocal rhythm technique Biz Markie is known for.

“Tommy said, ‘Will, you know that mouth-beat thing you do? Wouldn’t it be funny if that was really an alien language?’ I thought, ‘Oh, yeah,’ and I went straight to Barry, who loved it, and we filmed it, and now it gets one of the biggest laughs in the film.”