Well I went over to a friend's house and we managed to swap it out...took about an hour. First we jacked up the car pretty high from the rear only. We dropped the drive shaft and 2 other brackets that are bolted underneath but don't actually hold the drive shaft, so a total of 6, 14-mm bolts. Before dropping the drive shaft, we used my aluminum racing floor jack to hold the tranny and lowered it slowly a few inches until it wouldn't drop any lower.
We had to use 2 pry bars, one to move the tranny toward the passenger side and another to pull out the speedo drive out. By dropping the driveshaft and hence the tranny, you end up having enough room to actually pull it out. Putting in the new one was "reverse as removal" a la the Fiat manual...
The problem with mine was that the post that accepts the square-shaped cable had become circular after years of operation, so the circle was just spinning over the square and thus, no speedo. It was amazing how smooth the part looked though...you'd almost think it was machined that way!
Moral of the story: 2 people, 2 jacks, and 2 pry bars.