I\'ve found many references online (including some on stackoverflow) to JNA being used for C++ libraries, but nothing I can find in the JNA docs indicates that\'s possible.
Youre right JNA is for accesing native libraries. I think what you need is a Java - COM Bridge. If this is the case there are a few free alternatives:
JCOM http://sourceforge.net/projects/jcom
Jacob http://sourceforge.net/projects/jacob-project
I've used Jacob in the pass with good results, but I think it's a little bit outdated.