While the labeling conventions would be that Cb would correspond to Pb, Cr to Pr, and Y to Y, the labeling on the component connections of the receiver/processor could be A-B-C or X-Y-Z or 1-2-3 or just about anything as long as the luminance (Y), red differential (Pr, Cr) and blue differential (Pb, Cb) information from your playback devices consistently end up at the luminance, red differential and blue differential inputs on your projector.

This jogs my memory regarding a trick I used a few times in the past to allow on-screen-menu information normally available only on the composite video output to be visible in black & white on a component display, that is if the composite connections on the receiver/processor are otherwise totally unused. Try running your Cr and Cb information as normal, but run your Y signal through the composite connectors instead of running the Y signal through the Y connectors.