First find the schimmy spot in the level you wish to do this. Then go to a top of a quartpipe then press r2 so u jump out of schimmy. then make ur way to a WJG(DONT GET ON BOARD) far away from the qp you pressed r2 at. Climb up the wjg until u get pretty high then get on your board and you will fly across the level. If you have a ULG spot between you. you will fly into it and get stuck inside it.