Full Color Screen Printing with Photoshop

http://www.screensilk.com/2007/01/full-color-screen-printing-with-photoshop/
"If you have read my article, “The Secrets to Full Color Screen Printing”, than you already understand the underlying principles to 4 color screen printing. In that article we discussed the principles of the CMYK color model, color separations, halftones, and lines per inch (LPI). In this tutorial, we are going to take what we have learned, and using photoshop, quickly create color separations for output to transparencies for screen printing."