I previously explained on how to use OCL when running EMF in standalone (not as an Eclipse application). This method works until Eclipse Luna. With Eclipse Mars, OCL was heavily updated again. For instance, it was promoted out of the examples space.

The good thing is it seems to be much easier to initialize it now. Add a dependency to org.eclipse.ocl.xtext.completeocl and use the following code:

PivotStandaloneSetup.doSetup();
CompleteOCLStandaloneSetup.doSetup();