POST QUESTIONS ON THE FORUM! COMMENTS HERE SHOULD ADD VALUE TO THE
PAGE!I now found out how you can make Middlegen use any Java class as a
generator. Simply add the class's name to both  of the following attributes:
standardGeneratorScheme
standardGeneratorArg

e.g.:
<hibernate 
  destination="${gensrc.basedir}" 
  package="${gensrc.package}"
  standardGeneratorScheme="at.xxx.TableIdGenerator"
  standardGeneratorArg="at.xxx.TableIdGenerator"
  javaTypeMapper="middlegen.plugins.hibernate.HibernateJavaTypeMapper"
  genXDocletTags="true"/>

Note that as soon as you change any value in middlegen's key generator
drop-down box, it will never again use your owb Java class (unless you
edit the properties file)