Yeah, I should've been clearer - I meant create two shaders and switch them in/out via script. Was more in response to Axios's post than yours, I just happened to have the links to the documentation handy as I'd been playing with similar stuff :) Although looking at it, you could maybe make a multi-pass shader - one pass…
Setting material states via code in Unity's really easy; http://unity3d.com/support/documentation/ScriptReference/Material.html Could just set up the shader to have a lerp as Keen mentioned and set it 0 or 1 via script as you please. Or switching material entirely;…