[Zope] multiple selection with methods

Hello all, Itseems really difficult to have some informations about multiple selection (i send a message and see an other one without response). Then i ask again: how could we insert a method (pyhton perl or DTML) from a particular place (but not directly placed in the Zclass definition, and with argument in an attribut definition (in a Zclass Object). The goal is, when we instanciate the object (in zope), the creator of the instance of the object could initialize the attribut we informations taken from a list. I need the syntax and the limit of possibility !! Thanks for your help Best regards Dominique Jouniot