It would be trivial to create your own xml schemas for "documents" for example. All you would have to do is to create an .xsd file like the ones for audio and video searches and put it into the xml.war (a renamed .jar file).

Making LimeWire secure is a llittle more difficult, I know the LimeWire developers have created an authentication method, for connecting to LimeWire but I don't never looked at it in detail.

Better ask them developers yourself at dev@core.limewire.org.

__________________
Morgens ess ich Cornflakes und abends ess ich Brot
Und wenn ich lang genug gelebt hab, dann sterb ich und bin tot

--Fischmob