you shouldn't have to much trouble with this on a standard board, doing it the normal way... but if for whatever reason you can't seem to mange go and get a DLC board (any will do but I prefer Sabre's) and then get in a couch/lunge
and lean side to side to navigate
you won't need to do jumps and tricks and just avoid the sides and your opponents should be left in the dust close to the start line.
obviously clear as many flags as possible, this game is pretty lenient you can pretty much ride the edge of the flags and it will still give you a pass.
heres my awesome paint pic to show you what it should look like side on (so 90 degrees from your TV)