Sounds quite complicated. Do you know for a fact that simply inactivating v.5 and activating v.4 (as in both installed) wouldn't work?
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.