Java Generator

I am about starting a new small sized project where I'm going to build a generator for Java classes. The classes will represent different transactions (as we call them) which in fact are different C-structs sent across normal socket.
We have a nice representation of the structures and transactions defined in XML files which in turn has a Schema file (xsd).

So my thought was to first generate the XML reading part from the Schema by using XMLBeans and then output the new Java classes by using Velocity.

Then it would just be the matter of writing some templates and glue the stuff together.

Anyone that has done something like this already and would care to give me any pointers?