How to run Epicor E4SE ICE 1.4 and ICE1.5 side by side

Recently I upgraded our E4SE V8.11 from ICE 1.4 to ICE1.5, after upgrade, I noticed that another sites which hasn't been rebuilt stopped working. Since we don't want to upgrade the other site, I need to figure out a way to make ICE1.4 and 1.4 run side by side. At the end, the solution is actually surprisingly simple, use the bindingRedirect settings in web.config, we only need to either install ICE 1.4 assemblies in GAC or simply copy to the 'bin' folder. ....................