Using "Rivals for Catan" extensions with "Catan Card Game"
It would be incredibly difficult to mix the old base game with the new expansions. While similar, the rules and mechanics were completely redone for Rivals. It may be possible, but you'd probably need to reword most of the descriptions for all of the cards in either the base game or the expansions.

By the time you've done all of that, you'd have been much better off just spending the $15-20 to get a copy of Rivals instead.