White House aides bounced by the coming purge will be able to move into high-paying, fire-proof career federal jobs without missing a payday - if they move correctly and fast.

Three keys are necessary to make the transition from removed-without-prejudice White House satffer to mid-rank civil servant:

- The would-be-mover must understand where new wider entry doors into the bureaucracy are, and how they work.

- He or she must have approval from their former White House boss that the change is acceptable.

- They must have help from the department or agency where they want to work so they can get quick clearance and approval so they go on the payroll the same day they leave the White House.

Hiring procedures for handling White House aides were liberalized this year (mid-February) to cut time and red tape. They make it easier for political appointees, confidential assistants and secretaries to move into career federal jobs. People with two years' service in the White House (or on Vice President Mondale's staff) can count their time as federal service, allowing them to skip the one-year probation required of new federal employes.

The process of leaving the political side of government for the career side is often called "burrowing." It usually happens when administrations change.

Many political appointees fled the Johnson administration for career service jobs under Nixon. And many Nixon and Ford appointees (some with career service, some without) "burrowed" into the career ranks when Carter was elected. But it is easier today for people with White House backgrounds.

Formerly, persons wishing to survive changes at the White House had to get clearance from the Civil Service Commission - now Office of Personnel Management - before agencies could hire them. It was usually just a formality, but it took time and left tracks.

Now, OPM has delegated hiring authority to individual agencies. It is up to them to determine if White House refugees meet "minimum qualifications." People with friends and contacts inside government can make the switch from the White House. But there must not be a break in service. So they must be put on the civil service roster the same day they leave the White House.

The relaxed hiring procedure comes just in time. On July 9 this column said: "The next sound you hear will be the noise that VIP heads make as they roll down government hallways."

The column warned that many people who came in with Carter would not be considered up to snuff to conduct a "holy war" against the energy crisis, and that new people would be brought in to help "erase the what-me-worry? image Carter has with many voters." It is happening now.

Big changes in the Cabinet, and White House staff, are in the works. And there will be subsequent shakeups in middle level jobs. Many people who are now political appointees are looking at the relative peace, quiet and security of the career civil service they sneered at - until they ran into trouble themselves.