Depends on your DB design and contents.
If you mean that you have a field that just contains sequential numbers (1,2,3,etc.), then yes, you'll have to manage it all yourself.
But it's not hard.
UPDATE tablename SET idnum = -(idnum+1) WHERE idnum >= 3
INSERT INTO tablename (idnum, other, fields) VALUE(3,'other','values')
UPDATE tablename SET idnum = -idnum WHERE idnum < 0
(You can't just directily bump the numbers by one, so you make them negative at the same time you bump them and then convert all the negative numbers back.)