It was minutes into WXIA's 6 p.m. newscast Monday night when news anchorman Dave Michaels said, "As you must know by now, this is Bert Lance."

A camera then closed in on the former Carter administration budget director and Georgia bank president whose signature was visible at the bottom of the television screen.

Referring to the almost 30 reporters and photographers clustered in an anteroom just off-camera, Michaels told the TV audience: "This is the first time in my years of presenting the news where the news has become the news."

Replied Lance, "Well, unless I call on the president to resign, everything is going to be an anti-climax after this."

To which Michaels said, "Well, go ahead. You're on the air."

It could have been the Dave and Bert Show. The repartee was bright. The smiles were effusive. The mood was ebullient. Finally, though, the camera panned away from Michaels for the last time and focused straight ahead on Lance. He was sitting behind WXIA's no light blue news set built especially for him.

Reading from a teleprompter, he addressed himself in general to the purposes of his three-times-a-week, three-minute commentaries, a job that reportedly will earn him between $50,000 and $60,000 a year.

I'm especially interested in expressing some of the concerns of mainstream America, Middle America," he said, "the great majority of people who respect the law, pay the bills, make the wheels of industry turn, fill out their own tax returns at no expense to the government and give their time and money to everything from the Boy Scouts to political campaigns."

He concluded by urging President Carter and Congress to reduce taxes immediately, not in October as the president's tax reform plan now suggests.

Lance's evening began when he pulled up to WXIA's studio in north Atlanta nearly an hour before air time. He was escorted by two security men into the newsroom for a lighting check. After spending several minutes on the set, he was hustled off to the office of Jeff Davidson, the president of the ABC affiliate. There, he retired to the conference room to make final editing changes on his three-page typed, double-spaced manuscript.

While the station's reporters hustled to meet deadlines in Monday night's unusually hectic newsroom. Lance made a few small changes in his manuscript. Finally, he pushed the script aside and talked about how his first commentary was written.

"I didn't spend a great deal of time trying to find the right word or expression," he said. "I don't have problems with writing. Especially when I'm expressing the concerns of the American people, writing comes easily."

Dick Williams, WXIA's news director, said the station had to make only a few changes in Lance's copy. "At first, it was too general and introductory in nature," Williams said. "And we asked him to change it, to put something substantive, because so many reporters were going to be watching him on this first night and expecting him to say something."

At the end of Lance's commentary, the cameras swung back to Michaels who read congratulatory telegrams from President and Mrs. Carter and White House aides Jody Powell and Hamilton Jordan.

And just how will Lance be received as a commentator? WXIA switchboard operators said calls before the telecast about the heavily promoted addition to the station's news format ran generally against Lance. Of the 50 calls immediately following the newscast, 35 were favorable and 15 unfavorable.

WXIA, an ABC affiliate which runs a poor third in the Atlanta-area news ratings, happens to be in the middle of a new rating period. By this morning, station manager Davidson will have a readout that may indicate how Lance scored Monday night. As for last night, Lance (he's on five nights this inaugural week) already had his script written. It was about the humanistic responsibilities of big business.