Just figured it out myself it should be /private/{your-account-name}/sbt-launch-0.11.2.jar. See http://wiki.cloudbees.com/bin/view/DEV/Custom+Build%20Tools under the section "Private Repository".
Jonathan, I uploaded my jar to /private/sbt-launch-0.11.2.jar, but my first build failed: "Unable to access jarfile /private/sbt-launch-0.11.2.jar"
Any ideas?
Until Cloud bees support it, you need to upload your own. To do this follow the steps below:
1. Go to Configure System, under Manage Jenkins
2. Under SBT click add
3. Give the new sbt version a meaningful name and for the location a path starting with /private e.g /private/liftmodules/sbt-launch-0.10.1.jar
4. Using WEBDAV upload the new version of SBT
This should now be available via drop down when creating or editing a job.