I am currently using Instruments via a bash script to initiate the command-line interface to start up runs of the Automation plug-in.
With 4.2, this worked well en
Adding to Alexander's answer, I found that for Mavericks, because of the way authorizations are handled (source), you should do this:
sudo security authorizationdb write system.privilege.taskport allow
I am running zucchini functional tests through a Jenkins job in a VMWare VM, and the slave couldn't launch properly the simulator and would hang on the splash screen, probably because of incorrect authorisations. This helped me solve this issue, hope it helps others.