The points to note when doing this are:
1: Have EXCELLENT straplocks, otherwise you'll do a "One Off"
2: As mentioned before, you need to throw the guitar more UP than around, and use your left hand on the heel to kinda make sure you don't throw it into the side of your head as you release.
3: LIFT YOUR RIGHT ARM UP AS YOU THROW!!! Otherwise your strap will slide down your body, and you'll hula hoop your guitar. Not a pretty sight.
4: When the guitar neck comes around, put your right hand down to grab the body, and reach all the way around to GRAB THE STRAP FIRST!!! If you grab the body, it'll hurt! You want to slow the guitar down as it comes around.
I've done this a few times, but only with my kramer focus $50 axe
Slidey straps help a lil to get it round, but if you can't catch the strap, it'll keep going (Usually onto the floor).
I ACCEPT NO RESPONSIBILITY FOR ANYONE WHO TRIES TO DO THIS!!!