Since when do you need a machine to lucid dream?
I am able to do it all the time (usually only for a few seconds though) by falling alseep in an uncomfortable position, so I fall asleep but am conscious enough to know it is a dream. It kind of feels like you are half awake. And, then I control what I want to dream about for a bit, usually whatever I was concentrating on really hard before I fell asleep.
On another note, Delta Force Snipers have been taught to control their sleep so that the mind tells it's body it is asleep, yet they are awake mentally and completely alert. The few reports on this indicated that not everyone could do it except for a select few that were choosen to be SFOD-D snipers and had to undergo weeks of treatment under a pyschcologist to be able to do it.