[Zope] Move project to another Zopeinstallation

Hi, I have to transfer a complete Zopeproject from one Zopeinstallation (v2.5.1) to another (v2.6.1). Unfortunately the person who managed the old Zopeinstallation hasn't left any documentation about what additional products and extensions he installed. So, a simple export/import of the whole project doesn't work. In a former post on this mailinglist I read something about copying the contents of Zope/lib/python/Products, Zope/Extensions and Zope/var/Data.fs from the old to the new installation. But after doing so and starting the new Zope process there occur many errors on the console and the process dies. Can anybody help me please? (If this is a FAQ, sorry.) Bye, Chris