[Zope-CMF] How to Override CMFDefault Content Class Methods?

[Yuppie]

Hi!

What I want to do, is to customize the behavior of existing CMFDefault 
content items, without
- touching the CMF Product
- converting existing content objects to items of a new subclass

The only way I know is the 'Scriptable Type Information' of the CMF 
Types Tool, but it just lets me customize the construction of a new object.

1. Is there a way to add/change methods of existing objects?
2. Will it be possible in Zope3?
3. Or shouldn't I do that for any reason?

Thanks.
	Yuppie