I have revised my space boot method - please visit my new blog entry here: http://columbiascloset.blogspot.com/2011/05/boot-toppers-revised.html
I can usually find a good base for about $40 on eBay. Ideally you want a black patent leather ankle boot with stiletto heels that has a center seam running all the way down the middle. But if you can't find that, aim for something with a pointed toe and a straight top.
I made my points out of 2-way stretch black vinyl and silver spandex - the forgiveness of the stretch is what will make them easy to work with. After you've sewn the black and silver points together and clipped the points and turns, you can turn it right-side-out and you'll probably want to steam them flat (with a pressing cloth!).
Now you're ready to attach the topper to the boots. With e6000 (or your epoxy of choice) apply the wrong (inside) of the vinyl to the outside of the boot. Yes, there will be a seam, but it's not going to be noticeable. Do not secure the silver fabric yet. Go slow - I recommend only securing a couple inches at a time and waiting for it to dry before you proceed.
When the points are secured, you can begin gluing the silver fabric to the inside of the boot. Careful not to obstruct the zipper. Once it's set, you can bend the 'leaves' accordingly.
I've added my zig-zag pattern to the Pattern Page, and you can see the finished boots in my original Space Boot entry.