Shader: Add Refraction to Surface shader?

Hi there!

I want to add Refractions to my surface shader but I have only a working Vertex Refraction shader here and I have so far managed to write surface shaders... I have no idea how Vertex shaders work and the problem is I need the refraction in my Surface shader....

Is that somehow possible and if yes how? What do I need to do? btw I have unity Pro if you ask.

thanks for any help.