1) first learn good b/s 180's so that you can do them nice and high.
2) you should also learn f/s boardslides first because their so much alike.
3) ok, push a few times get some good speed.
4) I recommend you try it on a double sided curb first then a rail.
5) go mostly parallel but at a slight angle.
6) Ollie up and start turning backside.
7) get your back truck over the object your trying to slide
8) now its just like a front side boardslide.
9) just balance your weight over the board and don't lean too much forward or back.
10) then when your near the end come off regular, roll away, make all your poser friends jealous and thank me. (note) this trick is pretty hard, it takes a lot of practice before you get good at it. so skate hard!
Good Luck!
By: goodfella
Click Here to View the Video – SSJoe