This trick isn't very useful, but it's fun to try. When you are small Link, goto Lon Lon ranch (in the middle of the horse area) and play Epona's song. The small will follow you for a while. Leave slowly out the gate to the horse area. If Epona leaves you, just play the song again before she gets too far. Turn right when you get out of the gate and go as far as you can before Epona leaves you. She will try to run back to Malon, but the fence will be in the way. She will keep running until you leave the area.