[Zope] How to convert Zope instance charset?

I have a Zope instance that uses utf-8 for everything. Since Python/Zope/etc practically doesn't support utf-8, I would like to switch over to ISO-8859-2 (for everything). The problem is that this instance is a fat site that is on-line for several months, so I have to convert the strings stored inside the lot of already existing objects of the ZODB. Any idea how to do it, like an already existing tool for it? -- Best regards, Daniel Dekany