Cold smoking is basically drying process to add smoke color and flavor to product. Sausage like salami, pepperoni, cured bacon and some fresh sausage can benifit from the process. Cold smoking is done at temp under 110 degrees or can last up to 3 days in some cases. The correct chemistry is needed to insure safe product. Cures like Tender Quick, and prague powder would be needed to insure that you keep bacteria growth to a minimum.
Setting up a smoker is needed, you have a number of choices, using a couple of verticle smokers one for sausage the other to generate smoke that you can pipe into the first cooker. An old refrigerator can be used with a smoke generator. If you really get into it a smoke house can be added to your cooker collecton.
Len Poli has a web site and msg board that gets into techniques and formulations, great resource.http://home.pacbell.net/lpoli/