Its much easier to use use a regular bean and add @Converter annotation to the class and the method(s) you want to be type converters.
See more here
If you have the Camel in Action book, then its also discussed in chapter 3.
Thanks for the comment.
I am using the @Converter annotation and that seems to work fine.
I am just trying to understand how the TypeConverter interface can be used.
By the way, I already have you book way when it was first released.
So, the question still unanswered.
End users is encouraged to use the @Converter and beans.
The TypeConverter interface is more for internal usages etc.
Camel will pick the Exchange method if its available, if not it will pick the one without the Exchange.