I would never want to do this. If I knew I was going to have to train early, I would set my alarm and get up early enough to get in a meal beforehand. At the very least I would chug a mixture of gatorade and caffeine.
One thing I have advised a friend to do who is in this situation is to eat a large, very starchy meal before he goes to bed. This gives him a good boost of energy in the morning. Not everyone can get away with doing that, but he's a skinny hardgainer, so it works for him.