Trick tip provided by Goin' Ballistyx! Snowboard Show.  This is one of my favorite tricks.  I do mine a bit different.  I put pressure on my toes jump into the spin.  If you put enough pressure on your toes and drop your shoulder into the spin you will go off axis.  If you plan on going off axis you should also be going for a 540.  Off axis 3s are possible 5s just look better.