I have just paid a subscription to JumpBox specifically for Alfresco. I too need Alfresco Share and the documentation all points to this being accessible on port 8080 but the JumpBox Alfresco does not have anything on port 8080. I also note that Alfresco is up to version 3.2. Do you have any idea why your version does not seem to have this functionality?
It sounds like you'd be better off asking your question over at the JumpBox support site, especially if you're a paid subscriber. http://www.jumpbox.com/support