I would read Stinky's thread on cloning first, the noob thread I believe.

In short I would:
- do it during the final flush for best chance of success
- choose lower shoot with very little flowering
- use razor blade to cut, sterilize with alcohol first
- cuts should be ~ 3 inches in length total
- cut at 45 degree angle and scrape gently the outside of the stem (bottom 1/2 inch)
- carefully remove buds, but keep the sun leaves
- after cutting and scraping, place stem in water immediately so stem doesn't close up
- use a rooting hormone (Olivia's or Root Tech gel)
- use peat pods or root cube, rockwool, etc (you want to be able to observe the roots growing out of the bottom of the medium
- place under CFL, about 6 inches from light
- keep very high moisture and 24 hour light (humidity tent using a baggie)
- keep the little cuts warm (I use a heating pad under the container - helps but not critial)

I will try to dig up some info for you on how to do it step by step. Most importantly, if needed lightly mist them regularly 2-3x daily to keep humidity high.

Expect that it will take 10 days or longer to see roots, maybe even up to 3 weeks. I might just have to try this to see tomorrow to see how well it works.