From the information in the different sources, I think I was able to put together the appropriate command:
I believe that is providing the IDs that I'd need to delete for all messages in that folder before 06/10/2007.
zmmailbox -z -m firstname.lastname@example.org search -l 1000 "in:/Folder/To/Search/In (before:6/10/2007)" | grep "\. -" | cut -f2 -d"-" | cut -f1 -d" "
Is there a possibility you can increase the maximum search result value to be much larger than 1000? When I enter 1001 it only shows 30 results.