Have a person in the middle (main handler) standing as if lunging normally, and have another handler the horse trusts at the horses head. The handler at the horses head leads and guides the horse out and leads them in the circle around the centre handler. Gradually reduce the influence of the handler at the horses head until the horse understands it is to work alone.
For trot, use the handler again and get them to respond instantly to the trot cue from the main lunger and lead the horse into trot too. Again reduce the influence of the handler at the horses head as the horse learns what is expected when given a cue to move up a gait.
For the turning in, once she has learnt how to lunge, everytime she turns inwards flick the line up to turn her head out and ask her on again. If she turns in when you have asked for halt, do lots of walk-halt-walk transitions and she'll soon learn stepping her butt outwards is a waste of energy as she'll have to turn back when you ask her forwards.
Btw, if you and your friend don't have much experience lunging, find a horse who knows what to do so you can learn off him. Its easy to get the line into spagetti loops when your trying to learn and teach at the same time!
Word of warning- don't confuse confusion and naughtiness. Confusion will probably turn into naughtiness if not handled right, or a confused horse might lash out which causes loss of confidence in both horse and handler, and its a lot harder to fix a problem than it is to avoid it!!
We lose ourselves in the things we love, we find ourselves there too ~Kristen Martz