Decal Renderer

So, I'm probably in over my head here. But, I want to give this a try anyway. I have very little experience working with vertices, and no experience with manipulating textures/materials in a script.... but theres always a time to take the first step.

Now, I've been using two resources to aid me: http://blog.wolfire.com/2009/06/how-to-project-decals/ http://answers.unity3d.com/questions/1065170/issue-detecting-vertices-with-bounds-1.html

And, my progress is pretty good: http://prntscr.com/adqpf6 (image, wouldn't let me add it)

That there gets all the vertices within the bounds. Still need to make the rotation work, at the moment it is as if the bounding box is always aligned with the axes.

Now, my question: is the best method of applying a decal to a surface to use the vertecies that are in the bounding box and add a relative, local height of .005f? I'm not really sure if there is another option to be honest. I mean, would it be possible to modify the materials of every object that is within the bounds?

So, if someone could guide me in the right direction, that would be awesome! Thanks!