I think your best bet is to have a look at the Typepad Help. I did a search of their knowledgebase for "meta tag" and came up with one article called "Adding Meta Tags to your weblog" that had a tip at the bottom that might do the trick. I don't the their system well enough to say for sure.
If that doesn't work, try contacting their support team, or finding a forum that deals directly with Typepad.
... Duane