We use a couple of cutom UserType objects in our system.

At the moment, we register them globally with Hibernate by subclassing a particular Dialect (say, OracleDialect, for example) and then calling the registerColumnType(int code, String name) method during construction.

But, now we want to make our app run on two different databases.
Is there any way to register our custom UserTypes?

The UserType registration is the only reason we subclassed the dialect, so if we could find another way to register types, we could eliminate that class.
I don't really want to write a dialect subclass for each database we want to support.