In both lightwave and c4d, color and diffusion each have their own separate channels. My guess would be that using multiply in the Carrara color channel (to multiply a color in source1 against noise in source2, for example) might accomplish basically the same thing? In general I think Carrara has a rather flexible/powerful material system although (especially at first) you can strain your brain trying to predict how things are going to turn out when you start mixing things (I think some of the higher end programs give you a visual, node-based overview of what's happening with your shaders and some even let you work at that level when building shaders and I wonder if something like that could be done for Carrara).