Shader: Cutout behavior mixed with masking behavior

I have researched for about 5 hours now, and can't seem to find the answer. I need a shader that casts shadows like your typical cutout shader but has varying degrees of transparency based off of a mask. A perfect shader would be the cutout soft edges if only it were not self lit. Any ideas of where I can look for further help on this. I have scoured the unity forums and the Unity Shader Labs.