If your shooting Video you have to set your camera to shoot at intervals... every camera is different, if its a recent Canon, it might have that option.
If your shooting film, you would have to set your self up with your regular exposure, and shoot 1 frame ever... what ever time you want.. 1 minute, second, 2 mins.... what ever you want the duration to be.
Just remember 24 frames= 1 second... so yea..
Time laps would be really crudy if you would have to do it by hand. but if you must you must. The best way is to have a extended control which is not directly connected to the camera. If it is, every frame will move, and be different from one another... THUS its better not to touch the camera..
What camera are you shooting with?
Maybe I can help you out better knowing then?