As Christian mentions, there are a few articles on this:
Mine (referenced in Christian's article): http://www.vcoteam.info/learn-vco/work-with-vco-over-ssl.html
VMware KB (based on my article): http://kb.vmware.com/kb/2007032
Follow the steps in the article and the end result will be a self-signed certificate that matches the hostname of your vCO server which should allow a number of things to work with vCO api over SSL 