Let us know if you mean just a really fast zoom, or a zoom where the subject stays the same size but the background warps - that would be a dolly zoom. A fast dolly zoom is difficult to do and generally requires two camera assistants (I've done it with one, but it wasn't super fast and it was still a pain in the a** and the assistant needs to be a pretty good focus-puller) plus a dolly and a dolly grip.
If you just mean a really fast zoom in, then that's a lot easier. You could do it by hand, especially if you're using a DSLR as the zoom throw on DSLR lenses tends to be small. The best option would be to hook up a follow focus unit to the zoom ring of you lens, then use a speed crank if you have one.
The make-shift method is to attach a long piece of 1" gaff tape around the lens barrel and let it tail out, so you have like a foot of gaff tape hanging off the lens and have some one give the tape a pull, just make sure your camera is locked down very securely.