Thanks to the hard work of Nicolas (@ndeloof ) - the Node.js ClickStack now supports multiple versions of Node.js.
Existing apps keep working the way they have (as always) - and apps using "-t nodejs" as the stack type will keep staying up to date, but if you need to specify the version of your app:
-R node.version=0.10.21
Will tell the platform to use that specific version of Node.js with your app.
As always - the ClickStart is the easiest way to get all this setup - which pegs the version to be 0.10.21 at the time of writing.