Installing a weldless sight glass kit isn't hard but there are a few important steps that you need to get right. It's much easier for me to show you how than to type up detailed instructions. I also show you how to apply the vinyl calibration numbers to the tube without making a mess.
Sight Glasses, Unibits, etc at www.brewhardware.com
JD's photography site: http://www.tallmanphoto.com