EMF allows to generate model code for a metamodel. A Java programmer then can implement method bodies for defined methods of a metamodel class. You can call such methods in any OCL expression and pass values as parameter to a method, e.g. you can pass an OCL- Sequence typed OCL value to a EMF- EList -typed parameter of a Java method. You just have to install your model code by exporting the plugins with the generated model code and copying them into the plugins -folder of mediniQVT. Do not forget to add the namespace URI of your metamodel in the QVT preferences.