The easiest way to do this would be using a function called Slew. By default it is assinged to key "Y". If it doesn't work go into your commands and assign Slew Mode to Y. What you can do in slew is move the aircraft into any position you want. Place your hang glider at about 500-1000 feet using the key commands then press "Y" to leave slew mode. The glider will start flying as if you jumped off a cliff/
If you think slew is too unrealistic, there is a way to change the towplane. I know of people who have used the Cub or DC-3 as the towplane in addition to the Maule for the different types of gliders that they fly. Also, you can use the Maule's speed to your advantage. Just keep the tow rope on as long as possible than use the extra speed to climb right after the cable breaks.
There are three hang gliders and one of them can takeoff by running. It's called Foot Launch Pilot. It comes up when you do select aircraft. Oh, I meen 3 that come with the hang glider package.