Is there a way to update amortize adjusments checkbox for mutliple asset lines?

It seems we have ran Generate Asset lines for a Project multiple times. What we are faced with now is we have 6800 lines in Mass Additions that are labeled cost adjustments for the group of assets associated with this project.  At this point we would like to amortize these adjustments and since these were not amortized before the box needs to be checked for each record in Mass Additions.  Since there are 6800 lines we do not want to do this manually.  Is there a systematic way this can be done more efficiently?