Last year I have created an extensibility package to simplify and automate the steps necessary to extend the vCAC IaaS lifecycle process with calling out vCO workflows. While this was mainly aimed at accelerating Proof of Concepts it has been since then broadly adopted in production environments. Since vCAC 6.0 it is part of the product and available for vCAC 5.2 as a separate download.
Since this is now becoming a very hot topic I am including here a very useful extensibility introduction video that was released by my colleagues from tech marketing almost three months ago.