The easiest way is to use a custom program to enter tis data as a mass data or use MM17 for each individual period to be updated. The hardest way is to manually update the consumption for each material. Either way the data resides in table MPOP, and is what needs to be populated.
To get the data go to the delivery get the delivered quantity, and the date of PGI. Remember MPOP uses period not day so you’ll have to round the date to the correct period.