Hey that's cool. I've done a quadrille before, plus a couple freestyles and a pas de deux. I really enjoy doing this kind of work...creating my own test and then putting it to music. If you have any specific questions I'd love to help. I choreography music for myself, plus for others as well. I've done all the research on the USDF rules for musical riding...so if you have any super-technical questions again feel free to ask!
My number one tip is practice. The more people you have, the longer it's going to take to get it right. Good luck!
DRESSAGE, n.: the passionate pursuit of perfection by the obsessively imperfect -Author Unknown