Here's a sub-optimal solution that I used in the past. It's somewhat unhelpful today because Microsoft removed the API / interface that worked "back then", but you might find some success with it today using a "scratch server" to get the email from "EML" format into, say, PST format with "EXMERGE":
Exchange 2000 / 2003 exposed the Exchange Information Store, optionally, as a file system (the "M: drive"). In Exchange 2000, this was actually exposed as a drive letter on the server, but in Exchange 2003 it was hidden by default (but you could go through a procedure to expose it again -- http://support.microsoft.com/kb/821836). Each mailbox was exposed as a filesystem folder with ".EML" files in each folder representing the emails.
I used this interface to import email from "Yahoo Mail" for several Customers who were migrating to in-house Exchange Server installations, since I could get the messages from Yahoo as a large pile of ".EML" files in folders in a ZIP file. I would unzip the files from Yahoo into a subfolder of the user's "Inbox" folder on the "M: drive" and the messages would become available in their Exchange mailbox.
In your case, I'd probably install an Exchange 2003 installation in a scratch Active Directory on some VM's or test machines, perform the import there, then export the mailboxes with ExMerge as PST files and import them into the production Exchange 2007 installation.
It's a bit outdated, but it's the quickest way I can think to do what you want to do w/o writing any scripts or using a heavily manual procedure, etc.