Don't do it! If you just GOT to do it, do a few GDs first. Dremels have caused much razor tragedy and heartbreak. Get some experience with that fiendish instrument before you apply it to a TI.
Don't get just one GD. Get a dozen. If you buy 10 or more they are $3.43/ea with free shipping, when you go right to this vendor's site instead of ebay: http://www.buyincoins.com/item/7076.html. That's where I get mine. Check your emails from them after the sale... there will usually be a discount code for your next purchase. The last order I got, I paid less than $3.06/ea for them. When you got a bunch of them not only do you get more practice but you don't have to get all bummed out if you destroy a couple.
If I were you I would cringe at the idea of putting a Dremel anyware near such a razor, maybe OK for a ****ty Gold dollar but seriously don't do it, there are many good video's on how to create good spine work I'll leave you a video on basic file work there are many more for you to look at.
OK. Thanks to all of you. I won't touch that spine!