Well as you can imagine, you can't just point the camera at something and make it speed up, so you can either film something until the tape runs out, then speed it up to your liking in your editing program, or record in intervals, say record for 1 second pause for 5 or different depending on what it is.  Or if you have a really nice video camera there is probably a time lapse setting that does all the intervals for you.
Also you can just use a still camera and take single shots in intervals, then combine them in a video editing program.  It's time consuming but I find it can make for some sick shit.
And a tripod is pretty clutch for any of that.