HI Celit -
Sorry I didn't see this post earlier - SPAM and all. Welcome!
I don't recommending prepping for the SCAT, outside of showing the sample questions in the booklet so that your child is ready to work the computer - not a problem for most kids these days.
I don't know about how VCI and PR compare to Verbal and Quantitative Reasoning, but I do know that SCAT is trying to measure reasoning, not knowledge. In other words, you kid may burn through the test and be ready to go in about a third of the alloted time.
The other thing worth figuring out and 'prepping' is if there is a penalty for guessing. I think it's totally fair for a kid to guess if there is no penalty. I don't remember offhand if that's the case for SCAT, but it'll be somewhere in the official website.
Good luck to your child!
Grinity