Can you use the Supplier Item number in place of internal item number in item number field on purcha

We have a need to enter the supplier Item number in the item number field on the Purchase Order form.   We are trying to have the same functionality as Order Management with Customer Item Number references.

Can this be done in Purchasing?   11.5.9.2  DB 10G     We have set up a cross  reference type of supplier Item and assigned an item to type = suppplier item but we can only see the cross reference from teh main navigator, not in the purchasing form.

Thank you!

Bill