Scarlets boss Phil Davies said: "He's a world-class rugby player and a top-class bloke for that matter. He has been brilliant to work with, it's great to have him back in the side.
"Stephen has proven over the course of time what he is capable of and he will do it time and again before he retires, which is a long way off."
Ulster's David Humphreys is the fourth highest points scorer with 554 but has been ruled out of this week's clash at Ravenhill through injury.
Ireland's Ronan O'Gara remains the undisputed points king of Europe with 815 points for Munster. Former Wales hotshot Neil Jenkins is fifth with 502.