What is the secret to how the VIP Scaler works, and can it handle 4:2:2 video?

I've used and am currently using the VIP suite pretty extensively. If you have any questions feel free to PM me. I've not found it so difficult. thepancake is correct that the scaler will not support 4:2:2. Page 5-19 of the user's guide states:

Color Pattern: One, two or three channels in sequence or in parallel as selected
in the MegaWizard interface. For example, if three channels in sequence is selected
where a, b and g can be any color plane: γ β α

So a color pattern in sequence or parallel but not both. So use the Chroma Resampler to upconvert first then scale. You could of course write your own chroma resampler if you'd like. That bit's not too difficult.

Now to answer your question "how the VIP Suite scaler function actually processes data with respect to a 4:2:2 video stream". It doesn't. But if you pass 4:2:2 through, it would not distinguish between Cr and Cb but instead assume them to be one and the same color plane. So your scaled result will have truly interesting values in the Chroma fields.

Jake