If you're a congressman ensnared in the Abscam scandal, you'll have to stand in a long line to denounce Melvin Weinberg, the self-described con man behind the episode. According to a copy of a book proposal about his life, Weinberg has made a habit of double-dealing, back-stabbing and hustling, beginning with his Bronx boyhood when he stole gold stars from his teacher's desk to show his mother what a fine student he was.

Things went downhill from there. Where Weinberg's father went into the window glass business, for example, his helpful son drove around town in a Cadillac, shooting out windows with a slingshot. Dad's business boomed. And for the last three decades, Weinberg has taken his talents around the world, building a reputation that only became generally known when the Abscam affair became public knowledge early this year.

"Mel Weinberg's touch in the Abscam investigation was as apparent as a hammerhead shark in the kitchen sink," claims the proposal for an authorized biography of Weinberg that a Newsday Pulitzer-Prize-winning editor, Robert W. Greene, is writing for publisher E. P. Dutton. "The budget-conscious government investigator cannot think in terms of Dom Perignon coffee breaks, authentic Louis XVI furniture and rented Lear jets as props for an investigation. The government mind tends more to Sears, Roebuck suits, dinner meetings at Schrafft's and discount rooms at the Dixie Hotel . . . Weinberg made the difference."

Weinberg reportedly made about a $600,000 difference -- the reported cost of a sting that featured yachts, hotel suites, Atlantic City parties and, of course, cases of cash for polticians and their middlemen.

Among the information Greene and Weinberg indicate will be included in the book:

Some politicians were not to be touched. To the frustration of Weinberg and the FBI agents working with him, Weinberg claims, Justice Department officials reportedly ordered them not to pursue leads that might have led to bribe allegations against House Speaker Thomas "Tip" O'Neill (D-Mass), Rep. Peter Rodino (D-N.J), Sen. Strom Thurmond (R-S.C.) and several other congressmen.

Weinberg promises to reveal details of how he brought congressmen -- and not just their middlemen -- into the open to accept or at least discuss bribes as government cameras recorded them.

He also tells the story of a front page newspaper photographs in Philadelphia of a female FBI agent working with Weinberg that almost ruined the crucial Pennsylvania portion of the Abscam sting.

At the same time he was working Abscam, Weinberg ran an unrelated art theft con for the FBI. In what the book proposal calls "a movie natural," Weinberg convinced three gangsters to exchange a million dollars in stolen art for $500,000 in cash. The exchange was to follow a ride in the gangster's private plane to an airport whose whereabouts was known only to the mobsters. The FBI, however, followed the plane, recovered the art and arrested the mobsters.

Weinberg, described in the book outline as a "raspy-voiced, cigar-chomping swindler from the Bronx," owed the FBI a favor. Indicted for fraud in 1977, along with a girlfriend, Weinberg pleaded quilty and was placed on probation after promising to work for the FBI should the bureau ever require his services. Shortly thereafter, John Goode, an FBI agent newly assigned to Suffolk County, New York, recruited Weinberg.

Weinberg told the agent, "You gotta go with class. We need a big front, offices, limousines, a private plane -- something a little different."

Perhaps not since the CIA plotted in the early 1960s with organized crime figures to murder Fidel Castro has the federal government worked with a confessed crook on such a wide-reaching scam.

But if one mobster had had his way a few years ago, there would have been no Weinberg to mastermind anything. According to Weinberg, a Florida gangster almost threw him out of a hotel window because he'd swindled the gangster's nephew, a Miami lawyer, out of $8,000. Only Weinberg's desperate invocation of a higher-ranking mobster's name saved him from death. At least a couple of congressmen probably wish the aggrieved mobster had not been so charitable.

Footnote: An editor at E.P. Dutton says a couple of chapters of the Weinberg biography -- which the proposal says will enjoy the exclusive cooperation of the FBI agents who worked with Weinberg -- are in hand, and could be in bookstores as early as next spring.