I don't like the rubber band method because it doesn't break the glove in evenly. Trust me, park your car on it, it'll be broken in as well as leaving it banded for a few days after just the first night. Repeat the process a second night, and the glove will feel like it's a couple of years old.
I've tried the rubber bands, but IMO they just didn't truly break the glove in when compared to the parking method.