Catholics believe thatfith cooperates with grace and that faith without works is dead. That is all found in Scripture, along with the belief that God WILL judge us according to our deeds.
Works naturally follow in the life of a saved person.
But, it has nothing to do with salvation.
For it is by grace you have been saved, through faith - and this not from yourselves, it is a gift of God - not by works, so that no one can boast. Ephesians 2:8-9
Poor James, his must be the most misunderstood letter in the New Testament!. What he's saying here is that real faith results in works. Therefore, if anyone claims to have faith but there are no works, that faith is not real, is dead. But notice that he does not say that without works there's no salvation! He might have put it a little bit different than Paul did, but they both were in the same wavelength, both inspired by the Holy Spirit so they could not contradict each other.
That said, my personal opinion is that salvation by works is a human invention, to make salvation easier to understand. I was brought up Roman Catholic and sometimes I am kind of "jelous" of my mom because when she needed something she would bring out the candles, ribbons rubbed on this or that relic... It is harder to just trust Jesus to keep me in the palm of His hand, to trust like a child, without trying to take matters into my hand.