Is there a way to mass freeze POs using UNCD field?

We would like to freeze the lines on purchase orders using the UNCD field so that MRP will stop generating messages for these specific orders.   Some of the orders can be 75+ lines, so populating this field one line at a time is tedious.   Is there any other option?   We specifically want to use this field since it has functionality in MRP that other solutions, such as status or hold code, do not have.

Thank you.