WITH THE REQUISITE amounts of guile and gall, members of the lame duck Congress have come up with an ingenious and expensive move that could line their pockets handsomely when they leave town in January. The plan, uncovered by Federal Diary columnist Mike Causey, would: 1) jack up the salary for each member of Congress by more than $10,000 -- to a total of $78,900 -- and 2) let members who had been defeated or who plan to retire in January cash in on a 7.7 percent cost-of-living raise that went into effect in September for already-retired federal and military personnel.

True to past grubby form, the members are playing down this version of the money game; and they have even thought up a way to package their gift to themselves so that President Carter might not be able to veto it. The idea, reported to have been cleared by Senate and House leaders, is to couple the congressional raises with raises for top federal government employees who have been unfairly stuck under a salary ceiling -- and to include it in a continuing resolution that Congress must act on before adjourning.

To answer any taxpayers who don't appreciate the benefits of this arrangement, the lame-duck lawmakers will surely cite their own collective thoughtfulness as a departing Congress doing something nice for the incoming Congress -- and never mind where the twain may meet. But even those members who won't be sticking around long enough to make much out of the pay raise would be able to use it in calculating their average salary for retirement benefits. This, along with that cost-of-living break that they're cutting themselves into, would mean lifetime annual annuity increases worth several thousands of dollars a year.

It all adds up to a rip-off -- and if it takes a veto by President Carter, complete with a call for another session to do it until they do it right, so be it.