Beyond the murkily worded communique issued early yesterday by five Western powers meeting here on Zaire lies the reluctant acceptance to shoulder once again the white man's burden in that ramshackle central African land.

"There's no alternative to the regime" of President Mobutu Seso Seko, a key European diplomat said privately in describing the basically neocolonialist view of the crisis. "So we have to support him in hopes of reforming him."

That kind of talk may sound frighteningly similar to the attitude of "sink or swim with Ngo Dinh Diem" that led to massive American involvement in Vietnam in the early 1960s.

In fact, the top American, Belgian, British, French, and West German civil servants here appeared influenced less by an African variant of the domino theory - despite the politicians' much-trumpeted fears of Cuban and Soviet meddling - than in trying to keep Zaire afloat.

Symptomatic was a senior American official's explanation that much of the estimated $100 million in emergency aid needed to prevent Zaire from collapsing over the next three months was earmarked for spare parts in short supply before the latest fighting in Shaba Province.

If world attention is now centered on the African troops being flown in on U.S. Air Force jets to replace Belgian and French forces, it is because the whites who keep the Shaba mines working refuse to stay unless adequately protected.

The conferees know, however, that under Mobutu, Zaire has become a kind of primer for Third World horror stories in negative development.

One of the main reasons Mobutu's troops looted and fled in the recent fighting was because the government had not paid them for months.

Many of the detailed measures discussed here privately will become much clearer when the same five nations - plus Zaire, Iran, Saudi Arabia, the International Monetary Fund and its World Bank - hold a crucial meeting in Brussels next week.

That meeting, planned long before the latest fighting because of Zaire's inability to reform, will invoke only economic measures on the surface.

As the senior American officials told reporters, however, "economic measures often have political implications." Pressed to say what measures were involved, he prudently argued that such disclosures would be impolitic before Mobutu himself was informed.

The idea is to put foreign technicians in key economic and financial positions in the administration - starting with the number two slot in the national bank to control foreign exchange outlays. Their goal would be to prevent the waste so long synonymous with the Mobutu government.

The French appear moderately satisfied despite the lack of enthusiasm for President Valery Giscard d'Estaing's fixation with formal machinery to police future military crises and dole out development aid to moderate African countries.

In little more than a year, thanks in some part to Giscard's forceful African policies, the Carter administration has abandoned its hands-off attitude towards Africa in general and Zaire in particular.

The senior American official mentioned the now standard post-Vietnam argument about congressional - and public - "hesitations" concerning foreign involvements.

But when asked about Giscard's muscular role in Africa, he smilingly said, "We have not criticized it."

Whether the principal Western countries long associated with Zaire - Belgium, Britain, France and the United States - prove successful in the long run, remains very much in the air.