Essentially its combining noth Craig Barrs Cavity method and Amir Abdaoui known as Choco edge highlight method to create the final Cavity map thats similar to the Cavity maps you get from Xnormals and Crazybump
Here is the result:
1) Select Mesh > Under UVs & Maps> Click New Operation
2) Check Ambient Occlusion Map
3) Add Selected on both Target Model and Source Model
4) Create the Cavity map first with the settings below in the first image on the left
You will have to adjust the Filter number to get best results. Cavity map should be set to 0.001 or
5) Goto Paint layers> Adjust Color by right clicking on Cavity layer. Purpose of this is to tone the white to neutral grey.
6)Next create the Edge Highlight Map with settings on the image on the right. Remember to set Filter to -0.001
7)Change the blending mode of highlight layer to Linear Dodge
8)Only Show both the Highlight layer and Cavity layer and nothing else> Export Channel Merged> Done you have your Cavity map.
I would like to extend my thanks to both Craig Barr and Amir Abdaoui for their methods which was essential to tutorial.