Creating purchase order manually

I need to create purchase order manually with an override on the delivery address. Delivery address is no longer a purchtable field. There is the deliverypostaladdress field which links to the LogisticsPostalAddress table. When I create a PO manually, to override the address, I think I need to create a record in the LogisticsPostalAddress, is this right? What method can  I use? I will be using a inventlocation address.