List of Parts Needed For P226/P229/P220
You can download this as a PDF file from the Downloads page. For the 220, you don't need an ejector, it's built into the slide stop lever.
The 220 has quite a few parts that are specific to it, and differ from the 226/229:
Locking insert, hammer stop spring, slide catch spring, trigger bar spring, hammer stop pin, magazine release, grip screws, grips, hammer stop, hammer strut, trigger bar, slide catch lever, decocking bushing, decocking lever. I think that is everything, hopefully I am not forgetting something.