I did the same thing with a regular wire cutter thing (don't really know what they're called, but some kind of smaller wire cutter), and it works great, so I wouldn't buy a dremel only for this. (Dremels are rather useful for other stuff though, so might be worth a buy anyways.)

Since I don't have any of those fancy switch openers I have to bend the LED forward a bit before opening the switch, but that works just as fine. :>