Hi xcraft,
Rob's right, there's no option to do that in the wizard. However, what I've done at several client sites to work around this is to recommend to the client that ALL shortcuts expire after one year. This keeps your Exchange guys happy, as there aren't 10,000 2-4KB shortcuts in Exchange mailboxes, and your backup guys happy, as their catalogs aren't having nervous breakdowns!
What I generally do is set shortcut expiry to add up to one year in conjunction with the age based upper limit. So, for example, if I set all items to archive after 3 months, I set shortcut expiry to 9 months, so that there are shortcuts in the mailbox for (generally) one year. Of course, manually archived items and items that meet the large attachment threshold or quota threshold (if you're using quota based or age/quota) will be a little different.
My experience has been that most people don't try to access messages that are older than 2 months. If they realize that they need a message older than that, they generally end up using a search tool on it anyway, of which Archive Explorer is an excellent option!
Best of luck,
v/r,
Mark