Different type of solution (and violates the "company is paranoid about software installs" comment), but there are a number of applications such as
EZ-Detach and
DetachPipe that can automatically save attachments to a location of the user's choice and insert a link to the new location. I use EZ-Detach and have tried DetachPipe (it's very nice) and they can both be configured six ways from Sunday. DetachPipe will even recognise instances where the same file is attached to more than one e-mail and save only one copy (while inserting links to it in all affected e-mails), further saving disk space. I've requested similar funcitonality for EZ-Detach and it is now on the developer's "to do" list.
The operation of these add-ons is seamless and DRASTICALLY reduces the size of a pst. Just a thought...