How to enable iPrint/IPP login with full distinguished name in

We are very happy using NW6.0SP5 iPrint, which requires users to login
with their full distinguished name to access iPrint printers (i.e.:
name.ou1.ou2.o). NW6.5 intruduced contextless login for iPrint/IPP,
which is nice if you have unique login names, but we haven't. There are
numerous containers with duplicate CNs , since every container
represents a seperate department.

The new contextless login feature is fine, but it should be optional.
Any idea how to disable it?