After training the two upper gates for a while, place your palms on your center of gravity (lower energy center), and practice sending energy to the lower two gates. Inhale with your mind in the lower energy center. As you exhale, put your mind a few inches below the soles of your feet. Distribute the weight between the ball of the foot and the heel.
Inhale, bring your mind into the lower energy center, exhale, put your mind and inch or two beyond the soles of your feet.
Continue with this process until you feel comfortable with the mind shifting from the lower energy center to the lower two gates, and then back again.