Set the sliding compound miter saw to "bevel" the uncut ends of the baseboards in preparation for scarf joints. Scarf cuts enable the baseboards to meet and overlap each other in a flat orientation with only a tiny visible seam. The bevel on the upper board overlaps the bevel on the lower board. Start with the sliding compound miter saw blade at a centered and vertical position and then tilt the blade at a 45-degree angle. Make the bevel cut on the four "upper" baseboards that will overlap, then tilt the blade at the opposite 45-degree angle to bevel the lower baseboards.