You can call these libs from LCDS or BlazeDS (or WebOrb too) using the RemoteObject tag and alittle server side config - check out the example apps deployed.
I would suggest creating a service facade layer of POJO, plan old Java objects, that abstract all your backend Java code/libs. Wrap any security you need at this facade layer too. Its not hard to do and with BlazeDS you can get it up and running in 15+- min and its free.
