It is commonly called a PIH swap (though the original PIH kit is long gone). I'm not real hot on the idea - it's easier and cheaper to get a tune (even one that mimics an A9L) and use it in the superior T4MO processor.
Of course, if you have an AODE, this will NOT work.
For a PIH kit, you need a fan controller, BAP sensor and a handful of other odd-and-ends.