Well, there's nothing amazing behind the processing really.
I started off with two images open in photoshop, performed a lab mode sharpen on one and then copied it to the other image as a layer. I then chose the original layer and performed a high pass USM sharpen and overlayed it as hard light. Then it was lots of playing with contrast and brightness, very little change to the colours. I did some extra work with topaz adjust plugin and layered ontop at around 20% opacity.
Sorry thats just from memory, I'll try to make a list of what I do next time. For one thing I'm sure it can be done in a less complicated way.