I'm sure this "could" be possible, using the P node for example. I'm not good enough using the shaders, but if i remember well, the P node allows to work with the height of an object. So the bottom could be wider than the top.

I'll try to look if there is a way to create drops, but as said, i'm not as good (by far not) as Ajax for example.

And if i remember well, Ajax did a Wet and Dirt shader in his "Shader Pack". It was for Poser 5, but i think it should work with Poser 6, with little adjustment.