Routines in infopackages

Hi all!!

I have this question; Im loading data to an infocube from a generic extractor that dont have method delta; I load all the information and I want to others loads are the diference (like delta) I know that is possible to put a routine in the infopackage that only load this diference; but I dont know how to create this; I dont find some example to do that or maybe a how to...

Thanks for the help

Monica