[errai-users] Adding Marshalling/Demarshalling handlers?

Is there any easy way besides modifying JSONEncoder and TypeDemarshallHelper to add something to convert a type for sending/receiving over the wire? I'm wanting to do a subclass of Date for a DatePicker and want to serialize it a String so TimeZone conversions don't need to happen on it since it'll default to midnight for whatever the server timezone is. It seems as far as TypeDemarshallHelper, I can just do a static add to org.mvel2.DataConversion, but for JSONEncoder is doesn't seem that easy since the handlers are added to a private Map. I assume on the client side, it's as easy as adding a CustomFieldSerializer (http://code.google.com/p/wogwt/wiki/CustomFieldSerializer)?