GOOD MORNING: George Lucas isn’t the only one readying more “prequels.” Steven Spielberg, Bill Hanna, Joe Barbera and Bruce Cohen are in the futures market as well. They’re not dealing in outer space, but rather in prehistoric space, or stones, to be more exact, “Flintstones.” I went back in time with them again on Stage 31 at Universal where Brian Levant was again directing the cartoon-to-live feature. This one, “The Flintstones in Viva Rock Vegas,” is set 10 years before the original and producer Cohen allowed they are already talking this (second) cast to return for a, you should again pardon the expression, “prequel.” Of course, it depends on “Rock Vegas” repeating the original’s B.O. which was a whopping $350 million world-wide, $130 million domestically. Cohen noted that this version is budgeted at $68 million, the first, at $50 — but, he reminded, the original would have also cost $68 million in today’s market! In case you’re interested, Steven Spielberg is definitely interested in seeing that this prequel equals the original, He was in on all the current casting as he was originally. And Hanna and Barbera are so interested they will also take roles in “Rock Vegas.” The current film winds with the wedding of Fred (“The Full Monty’s” Mark Addy) and Wilma ( “Third Rock From the Sun’s” Kristen Johnston). Joan Collins and Harvey Korman play Wilma’s parents. Stephen Baldwin as Barney Rubble, Jane Krakowski (“Ally McBeal”) as Betty, “Dharma & Greg’s” Thomas Gibson as Chip Rockefeller and “Cabaret’s” Emcee on B’way Alan Cummings as the Great Gazoo. I came upon them all in a giant (40′-long ) banquet hall, created spectacularly by production designer Chris Burian-Mohr and all outrageously, formally attired in the latest (earliest) prehistoric fashions by Robert Turturice. While most of the action is “live,” Jim Henson’s Creature Shop designs 12 new prehistoric puppets, plus Dino, as a mere pet baby dinosaur in the prequel. Rhythm & Hues handles visual effects. Jamie Anderson is d.p. The film will undoubtedly be PG-rated. The banquet set was also a perfect site to celebrate Joan Collins’ birthday (66). And coincidentally the scene called for her to be thoroughly doused with food as Dino disrupted the party! Collins, as always was a great sport about it — and a huge birthday cake followed. Collins, in this 10 years earlier version, plays the role Elizabeth Taylor originated. Joan is svelte and sexy, and, noted “I am 10 years younger than Elizabeth.” (Actually, only one year younger, my dear). Collins’ latest novel is “My Friends Secrets” and her script, “Jealousy and Hate” (about two actresses, natch) will be a Showtime/Granada telepic. She will, of course star. “But what I really DON’T want to do,” laughed Collins — “is direct!” … Baldwin, in real life, is covered with tattoos (I mean covered!) requiring the makeup department to thoroughly spray him with heavy makeup each day. (Some designs manage to even eke through during the shooting day!) … Before returning for “Dharma,” Gibson will also feature-film “Psycho Beach Party”! And Korman, who interrupted his national tour with “Carol Burnett Show” partner Tim Conway for the “Flintstone” feature, will resume on its completion.WALTER MATTHAU IS RECUPING from pneumonia and should be released from the hospital in a few days, says his wife Carol. Matthau is costarring in Col’s “Hanging Up” for director-costar Diane Keaton. I am told Walter will not be needed for one remaining scene — in a gurney … Mike Medavoy underwent surgery Monday at Cedars-Sinai to repair a heart valve … A.J. (Angela Jennifer) Lambert, announced her engagement to Joel Friedman, of Williamson Music. And last Friday, A.J. celebrated her 25th birthday with her fiance, her mom, Nancy Sinatra, Jr., her grandmother Nancy Sinatra, Sr., her sister Amanda, aunt Tina, Michael Erlinger and Michael Allen at La Dolce Vita in BevHills. Saturday, Joel’s parents, Sherry and Bruce E. Friedman held the engagement party at Lunaria. Nancy Jr. sings at the Children of Kosovo benefit June 11 at St. Anthony Croatian Center on N. Grand Ave. She also joins KIIS-FM’s “Wild Wild Wango Tango” June 12 at Dodger Stadium. The all star lineup: Ricky Martin, Will Smith, Enrique Iglesais, Dru Hill, Britney Spears, 98 Degrees, Blondie, Fabrice Morvan, Shaggy and UB40 … Warren Beatty is among speakers Thursday at the Santa Monica restaurant Back on Broadway, at a fundraiser for International Medical Corps working in the Balkan refugee camps. Also speaking: Dr. Jeff Colyer, recently returned from working in a camp. Stanley Sheinbaum and Back on B’way owner Fred Deni host. Beatty and Steven Spielberg recently brunched at the Polo Lounge. Topic of conversation: the late Stanley Kubrick. EVERYONE LIKES A CIRCUS – especially when it’s Kenneth Feld’s Barnum’s Kaleidoscape, tented in the heart of Century City — and held over through June 6 before moving up to San Mateo. At the same performance to which we took our family, Tom Hanks and Rita Wilson brought their two children and her parents, with the Hanks youngsters joining in the finale. And Geena Davis was a participant in international clown David Larible’s comedy plate-throwing act. Other celebs on hand over the weekend included John Travolta and Kelly Preston, David Kelley and Michelle Pfeiffer and Lois and Art Linkletter … .Nancy Davis’ “Race to Erase MS” at the Hard Rock in Vegas over the weekend raised a record $3 million!