MVC :: Override Model Binding Failures Default Error Messages?

I am new to ASP.NET MVC and using ASP.NET MVC 2 with XVal. I am not using DataAnnotationsModelValidatorProvider and instead using NHibernateValidatorNHibernateValidator attributes. I would like to know that, when failing to provide a value for a non nullable type, how can i override the vanilla messages.There are actually two scenarios for non nullable type with model binding failure

1) when the data the user entered isn't compatible with the data type (for example, typing in "abc" for an integer field). The default message for this is: "The value [AttemptedValue] is not valid for [Property]."

2) when the user did not enter any data for a field which is not nullable (for example, an integer field). The default message for this is: "A value is required."

I know that the [Required] validator from DataAnnotationsModelValidatorProvider is treated specially during model binding failures on non-nullable types, so that you're not stuck with the vanilla message 'A value is required.'.

Also The DefaultModelBinder uses [Required] attribute for the second scenario only.Since I am not using DataAnnotationsModelValidatorProvider, I can not use [Required].Bearing in mind that I am already doing all the attribute validation and other business rules validation in my domain layer using XVal , What are my options here?

- Allow the model binding validation errors to occur, and then ignore and remove them from ModelState in my action method and refill it with my custom validation errors?

- Derive a custom model binder from and defaultmodel binder and override the onModeUpdated method ignoring all the validation?