I haven't tried doing this myself using either tool, so I don't know the exact answer, but searching for VPC in the github issue tracker for kitchen-ec2 seems to outline all the required components. (And you can see people are actively using VPC setups with kitchen-ec2, so if it were me, I'd contact some of the people who submitted stuff for more detail...and perhaps collaborate on updating the kitchen-ec2 documentation *grin*):
The most promising seems to be this thread where actual .kitchen.yml files are discussed in detail, and the thread is pretty recent (2 months ago):
doesn't invoke test while using ec2 driver. If it were me, I try the last one in the list, tweak the security_group setting as he mentions, and see if that works (and if not contact JigarJoshi with more questions):
Also, here's some older ones...
Adding subnet_id option for use with VPCs:
In VPC groups must be specified by setting :security_group_ids rather than :groups
Support selection of private IP:
Use private ip if the public ip is nil: