I did it! I made this gorgeous pair of slippers in less than a day to give to my mother for Christmas. They took me a little longer than 90 minutes to do the actual knitting than the Yarn Harlot site suggested, but they're done and quite lovely. I'm confident the knitting will take less time if I make another pair. I've felted with Lamb's Pride yarn before, but I may have just fallen completely for the Paton's Classic Wool used for this pair of slippers. Without having very much time or four days to block them, I used the household hairdryer to speed the process along a bit. I have exactly enough yarn (in two colors) to make two more pair.
The best part of this is that my mom was pretty shocked & loves them.
If you're interested in finding the pattern, please visit the designer's etsy shop: French Press Knits