Remeber chi is only energy it can be used any way imagineable, with enough practice and awareness of course. If you want to practice using chi in attacks try excercising using chi. For instance do finger push-ups and either visualize the chi going into your fingers, or if you are a higher level just concentrate on your fingers. Also practice combos on the heavy bag or ion the air and visualize your chi leaving your leg, hand, etc. when you strike. Just practice with it. There is not one set method that will work. Energy is limitless, experament practice and become more aware.