[Koha] Item information in 852 field

Hello. I'm the librarian at the Griffin School in Austin, Texas (a small a college preparatory high school with a focus on the arts). We recently successfully migrated our MARC21 records from Book Systems into Koha. We did *not* succeed in bringing individual *items*. Looking at the Book Systems MARC records, I see that the item barcode and call number are located in the 852 field. Is there are way to bring these into the Koha default 952 fields? Alternately, is there a way to batch create one item each for each of our bibliographic records? Thanks much for your suggestions in advance. Ingrid Karklins Griffin School Librarian ingrid@griffinschool.org