You want to adapt org.jmol.multitouch.ActionManagerMT to your purposes. You can see there that there are options right now for Molecular Playground, tablets, and SparshUI. I think you would logically add another. Your  client will only interact with ActionManagerMT.
OK, I'm slowly figuring it out.  I didn't want to start editing ActionManagerMT yet, so I created a temporary hack for my own experimentation - a stub clone called ActionManagerNI.  I changed the reference in Viewer from MT to NI and it looks like that's the only change I need to make to test on my own.  Now the problem is missing classes - I see that dropping jars into jars/ makes them available at compile-time, but when I try to run it, I get a java.lang.NoClassDefFoundError for OpenNI classes.  Do I need to modify build.xml or a classpath somewhere?