Hi James, like promised - here is the solution, which is rather simple but took us quite a long time to realize due to some lack of basic documentation on Spring Cloud Foundry.
First, you should configure Spring to read your VM argument using a property placeholder. for example if you're trying to decide which properties file to load using a VM argument, it will look like this:
then all that's left is to specify JVM arguments, e.g:
on the Cloud Foundry deployment configuration - and you're ready to go.