You can still launch Preps 5 from within Prinergy and use it exactly as before. You just have to set it up in the imposition setup within workshop. You can have it list both Preps 5.x and Prinergy 6.x in the imposition setup and then pick the version you want it to launch when you go to create/edit an imposition. You just want to make sure and copy the Preps 5 folder on your Mac to another folder named Preps 5 because the default Preps folder will be overwritten with Preps 6 when you install workshop.
OS: Mac OS 10.8.4 - RIP: Prinergy Connect 5.3 - CTP: Luscher XPose! 160 (2)