extending pg_type - Mailing list pgsql-interfaces

hi there,

I would like to extend the Postgres system catalog pg_types with the two
fields wwwin and wwwout for interfacing all Postgres types directly with
HTML. Is this possible? Are there too many changes necessary to make
this work? Is this the straight forward way to use the overloading and
resolution mechanisms for new system wide attributes?

Thanks for any suggestions!
Wolfgang