Using Code Editor to Alter Vanilla Mob AI

I made an item element of sorts and then had a procedure added to it which triggers when this item is right-clicked on a zombie. I want this procedure to change the zombie's AI somewhat, such as making it follow a player when holding a certain item. Is there a line or block of code I could input into the executeProcedure section (where all the code for the procedure events themselves go) of the procedure's .java file to alter a certain mob's AI like this (or at all)?