Spring create scoped proxy bean programmatically

In spring is possible to define scoped proxy bens as described here:

@Service
@SessionScope(proxyMode = ScopedProxyMode.TARGET_CLASS)
public class MyBeanClass {
    // ...
}

I really would love to do the same thing programatically, e.g. when registering a bean with an ApplicationContextInitializer.

public class MyInitializer implements 
    ApplicationContextInitializer<GenericWebApplicationContext> {

    @Override
    public void initialize(GenericWebApplicationContext applicationContext) {
        applicationContext.registerBean(MyBeanClass.class, beanDefinitionCustomizer -> ....);
    }
}

Is this possible? I haven't found any public API to do so...