how to post a packing slip for purchase order for customised fields in ax 2009?

hiiii…i am new to Ax.i have added a two custom fields in invent table and purchline table.in purchtable form design also i have added those two fields in line table.now i want to post the packing slip for purchase order along with these two custom fields and i need to maintain this in history.how can i do? what are the classes and methods that are needed to change?