If memory serves, the DXL exporter code in R6 wasn't able to export outlines in the "nice" DXL format, but rather in "raw" note format only (which is really only good for round-tripping to be able to import it again properly). Not sure when it will be available in the "nice" format.
PS: DDSearch 2.01 might already do what you want to do (it uses DXL, too)
http://www-10.lotus.com/ldd/sandbox.nsf/0/f090b24ea76b1c0100256c45003e6396?OpenDocument