Not long after the bullets stopped flying at the Dominican Embassy in Bogota, U.S. Ambassador Diego Asencio and two other diplomats held hostage by leftist guerrillas there began to act as consultants, of a sort, for their image-conscious captors. They even wrote a "first draft" for the demands that eventually led to their safe release.

Asencio shared that and other revelations about his 61 days of captivity yesterday as he returned to Washington for a hero's welcome from Vice President Mondale, Acting Secretary of State Warren Chrisotpher and throngs of his colleagues in the Foreign Service.

For the progessional diplomats, with their chief resigning and dozens of their colleagues held hostage in Iran, Asencio provided one of the few occasions for jubilation they have had recently.

As hundreds of State Department employes filled the balconies and lobby of their headquarters building, applauding and cheering, Christopher gave Asencio a plaque, eventually to be replaced by a gold medal, "for valor."

The wry, personable Asencio, a solidly-built man with a salt-and-pepper beard he grew in captivity, responded that he would not recommend this particular route to a medal."If it weren't for the honor, I'd just as soon skip it," he said.

"My relief is great at being free, but it is very much tempered by the fact that I don't think any Foreign Service officer can consider himself truly free while his friends and cohorts are being held prisoner in Tehran."

In a subdued but warn ceremony earlier at Andrews Air Force Base, Mondale haled Asencio as "a hero, a man of courage and as a symbol of the finest in American character."

The vice president took the opportunity, as well to say a word about hostage-takers, underscoring the administration's new hard line."Terrorism and the taking of hostages, whether in Bogota. Tehran or anywhere else in the world, are inhumane acts. They must be condemned. They must be combated. They must be stopped.

"We must measure our own civilization by the force with which we separate ourselves from barbarism," Mondale said.

Asencio, asked how he would have felt about a mission to rescue him similar to the one that failed in Iran, said he had mixed emotions.

"I felt it would result in considerable casualities," he said, referring to his own circumstances. "With my colleagues [other hostages], I decided instead of getting tough, lets get smart. We had the experience. They had the muscles, the grenades, the dynamite, the bombs."

He said he had no direct evidence that his seizure was inspired by the Nov. 4 takeover of the U.S. Embassy in Tehran, "but I think it probably influenced" the Colombian guerillas.

Asencio and the Brazilian and Mexican ambassadors are credited with forming the "brain trust" that helped guide the successful negotiations from inside the leaky old mansion where they were being held.

He also reportedly entertained his feelow hostages (more than 20, including 14 ambassadors, at one point) with jokes and stories. "I am something of a backslapper," he chuckled yesterday.

Indeed, if the nation were not distracted by its failure and fears, Asencio might be more raucously acclaimed by the public as the source of pride and good old American spirit they have been seeking.

Yet, in his low-key, good natured discussion with reporters at the State Department yesterday, he portrayed his ordeal in no more dramatic terms than a television sitcom.

Of his relationship with the guerrillas, he said conversationally, "I thought it important to make friends with them and make it more difficult for them to kill us . . . and also perhaps to create some doubts in their minds" about their ideological approach.

From time to time, he said, the captors would go out and negotiate and "then come back and tell us and ask us for our advice. And it was often taken."

At one point, he said, the guerrillas planned a harsh diatribe to introduce their demands. The three brain-trust ambassadors "convinced them it was completely unacceptable and would foul up the negotiation and that they would be taken for savages.

"Whereupon they asked us for a first draft of what we would say . . . and we provided it. And that was the beginning of the successful negotiations," he beamed.

Asencio said he and his colleagues also convinced them that the exchange of political prisoners they were asking for "would put them in the category of mere bank robbers. We persuaded them they could help create a historic agreement . . . something that would be helpful and would give them a rather statesmanlike cast.

"That was a rather tough one to sell," he said drily, but they finally accepted it."

The release, mediated by the Inter-Amrerican Human Rights Commission, provided for observers in Columbia to monitor the trials and treatment of guerrillas and is unofficially reported to include the payment of up to $2.5 million in privately donated ransom.

The 16 guerrillas who seized the embassy initially had insisted on freedom for 311 "political prisoners" and a $50 million ransom.

Asencio, a graduate of Georgetown University and father of five, said that after the first couple of "hairy" days, when he thought "it was all over," things settled down and he was treated well.

Physical conditions in the rundown old embassy, he said, were awful: "The roof leaked, the floors were rotted, there were few johns, no hot water, hygiene was very poor, and it was crowded."

Asked how he feels about his captors now, he said "Well, some were rather mean machines, others were interesting and attractive (young idealists) and other were -- just colorful . . . I've described them as 'radical chic' with guns."

His advice to other diplomats who may be seized in the future: During the first few minutes, lie very close to the floor . . . Remember you represent the government . . . Don't become passive . . . Exercise."

Asencio said he does not know what he will do next. "As soon as I get out of here, I'm going to wander down the corridor and try to find out."