Here's a patch for discussion. It's incomplete, but shows the basic idea.
The LocalService class is an implementation of Service that bypasses jclouds and implements launch and destroy for a local machine. It might be possible to use the forthcoming BYON code for this at some point.
There is a new destroy-zookeeper script to tear down a local installation (this is not needed in the cloud since the instances are simply destroyed).
Run it using
mvn verify -Pintegration -DargLine="-Dwhirr.test.provider=local"
You can also specify an identity of "root" and the root password as the credential to avoid having to enter them interactively.
I got the integration test passing on a Mac, and there are a few changes to make the script work there (there are still some spurious changes that still need fixing though).