So not having had much luck with the perl or python scripts on the wiki I found a script here that converted my MBOX files to maildir, I have then been able to upload to different people's mailboxes with the command:

zmmailbox -z -m <user>
createFolder /Imported
addMessage Imported /tmp/oldmail/.maildir/cur
However, when using this method I found that I received a message saying

ERROR: service.FAILURE (system failure: Failure Indexing: com.zimbra.cs.mailbox.Appointment@1e29df9)
on one occasion. This was about 700 messages in out of 1655 messages. As it imports them in a seemingly random order I have no idea which message this would have been as they are all labelled in numerical order and the import looks like:

694 (/tmp/migration/test2/.old_MBX/cur/1208526616.000833.mbox:2,)
695 (/tmp/migration/test2/.old_MBX/cur/1208526616.000143.mbox:2,)
696 (/tmp/migration/test2/.old_MBX/cur/1208526616.000879.mbox:2,)
697 (/tmp/migration/test2/.old_MBX/cur/1208526616.000783.mbox:2,)
698 (/tmp/migration/test2/.old_MBX/cur/1208526616.000600.mbox:2,)
699 (/tmp/migration/test2/.old_MBX/cur/1208526616.000790.mbox:2,)
700 (/tmp/migration/test2/.old_MBX/cur/1208526616.000748.mbox:2,)
701 (/tmp/migration/test2/.old_MBX/cur/1208526616.000882.mbox:2,)
702 (/tmp/migration/test2/.old_MBX/cur/1208526616.000551.mbox:2,)
703 (/tmp/migration/test2/.old_MBX/cur/1208526616.000660.mbox:2,)
704 (/tmp/migration/test2/.old_MBX/cur/1208526616.001155.mbox:2,)
705 (/tmp/migration/test2/.old_MBX/cur/1208526616.000559.mbox:2,)
706 (/tmp/migration/test2/.old_MBX/cur/1208526616.000348.mbox:2,)
707 (/tmp/migration/test2/.old_MBX/cur/1208526616.000347.mbox:2,)
708 (/tmp/migration/test2/.old_MBX/cur/1208526616.000850.mbox:2,)
709 (/tmp/migration/test2/.old_MBX/cur/1208526616.000925.mbox:2,)
710 (/tmp/migration/test2/.old_MBX/cur/1208526616.000028.mbox:2,)
711 (/tmp/migration/test2/.old_MBX/cur/1208526616.000663.mbox:2,)
712 (/tmp/migration/test2/.old_MBX/cur/1208526616.000060.mbox:2,)
713 (/tmp/migration/test2/.old_MBX/cur/1208526616.000159.mbox:2,)
I thought it might be date order but those last 2 messages are both in August but one is 2006, the other is 2007.

Now I can get the messages in to the persons Inbox via the aforementioned Python script but obviously it makes it easier to automate if I can do it all in one run this way.