That I took when I was in the exact same position:
Lost Porsche Keys
I lost (...really think it was lifted...) my one and only key and the nearest dealer is more than 150 miles away. I was not at all thrilled with the idea of having the car towed all that distance and then spending another $400-$600 at a minimum getting a new key made and coded.
The site above will walk you through the details but basically, you pull the lock mechanism from your door, pull the alarm module from under the driver's seat - ship those off. A few days later you get all the parts back and two new keys. The key blanks they used for my keys were for VW and not Porsche - but frankly I could not have cared less.
It takes a little fiddling to get all the parts pulled and then reassembled when you get them back, but, I'm no mechanical genius by any stretch and it wasn't too difficult for me. Their instructions are really good.
Feel feel to PM me if you would like any further info.
ajb