This is actually an easy trophy if you just want the trophy and don't want to go through all the hazzle of doing it legit (no ones judging)
The video below explains a very easy way to do it, so no excuses for not having this trophy yet! Go get it! =D
If you want to finish it legit though there is a video by Maka91Productions that goes through training the new FMX system a little bit and then giving you a few pointers towards this.
Good luck and happy trophy hunting =)