AFAIK you can not just "move" the data from one server to the other (one being 32 bits and the other 64 bits) because the LDAP data format is not the same between 32 ans 64 bit.
So you can either:
. migrate to Ubuntu 8.04 LTS 32 bits (and not 64 bits)
. find the correct way to export/import the LDAP data (as you say the current way that is in the wiki doesn't work)
. open a case by support as you're an NE customer
What are the exact error messages (and/or issues) you're running into while trying to export (and/or import) LDAP data in 6.0.1?