They are inside the hibernatetools-*.jar.
Unzip that jar.
copy the hbm2java directory into your own directory, i.e. "templates" so you have templates/hbm2java/*.ftl
Now use "templates" as your template path in hibernate code generation.
It will now look in this directory before looking in the jar.
Meaning you can add things into these *.ftl files and they should show up in your generated entities.