How to resolve a xpath reference given in an attribute

Hello,

I'm currently responsible for updating a database containing serialized java objects. Serialization was done with XStream. XStream uses references in the xml hierarchy to avoid objects to be serialized more than once in a complex object tree. The reference is a relative xpath. There is now the problem: Since current object structure has changed in meantime, I try to update the XMLs using XSLT. The references need somehow to be resolved properly when doing, to avoid that they point to places in the XSL that no longer exist. Or does someone knows a better approach? How can I access a node using the string given in the reference attribute?

ciao!
Kai