I found a solution using reflection. We create the RuntimeEnvironmentBuilder, use reflection to get the KnowledgeBuilderImpl and use this object to build and get the Process. After that use the knowledgeBase to deploy de process in runtime.

RuntimeEnvironmentBuilder builder;
builder = RuntimeEnvironmentBuilder.Factory.get()
                .newDefaultBuilder()
                .entityManagerFactory(emf)
                .userGroupCallback(new ScaUserGroupCallbackImpl());//my implementation of UserGroupCallback

//create RuntimeEngine with builder
...

//use reflection to get the kbuilder(KnowledgeBuilderImpl)
Field f = null;
        SimpleRuntimeEnvironment simpleRuntimeEnvironment = (SimpleRuntimeEnvironment) builder.get();
        try {
            f = SimpleRuntimeEnvironment.class.getDeclaredField("kbuilder");
            f.setAccessible(true);
            kbuilder = (KnowledgeBuilderImpl) f.get(simpleRuntimeEnvironment);
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }

//to deploy in runtime:
KnowledgeBaseImpl knowledgeBase = (KnowledgeBaseImpl) ksession.getKieBase();
Resource processResource = ResourceFactory.newClassPathResource("test2.bpmn2");
builder.addAsset(resource, ResourceType.BPMN2);
Process process = kbuilder.newKnowledgeBase().getProcess("test2");
knowledgeBase.addProcess(process);