Hi (vakbroeder ;)
Have a look at the codegen_settings.xml file located in the _devtools folder.
Lookup the following line and change the prefix attribute to suit your needs:
<!-- Other -->
<stripFromTableName prefix="tblprefix_"/>
You can also define multiple databases to be generated by adding a new <database index='dbConnectionIndex'></database> to the <datasources> node. You can then define another table prefix for this database if you'd like.
Note that you can also set another database connection by setting the index attribute of the database node to a corresponding DBConnection in your configuration file
hope this helps
Gert