Special shaping or molding heads can be purchased for table saws. These are rather sturdy hubs that hold three matched blades of any of a wide variety of shapes. These can be standard coves or ogees -- or tongue & groove heads. The variety available is almost as wide as what you can find for a true shaping machine.
One thing to note is that a shaper will spin much faster than your table saw, and a router will spin even faster -- but because of the different diameters of the bits or blades, the cutting edge actually moves at about the same speed through wood -- hence the reason for the 6" diameter on the table saw shaper hub. A 9 inch hub would move too fast for the shaping action and burn the wood.