Ride to the object Bs with your feet in ollie position.  This trick is a variation of the ollie bs boardslide and isnt much harder.  When you reach the object, pop a Fs 90 degree ollie and land in bs boardslide position.  Now's the small difference, you want your board to be overrotated so it passed the 90 degrees positon.  To land you can just land fackie or rotate your board back to normal wich is easier.  Good luck