Just google, or
http://alcoholinjectionsystems.com/ has a lot of information on it. For your purposes, you can just rig up a cheap system like I've kinda outlined in the knock thread. It is very simple, and works wonders.
http://www.ebay.com/itm/Devils-Own-Universal-Stage-1-Water-Meth-Or-Alcohol-Injection-Kit-SQ1-5001-/331203838801?hash=item4d1d498351&vxp=mtr