i'm in your conscience
It's really difficult for me to give directions to anything, driving somewhere, gym puzzles, you name it lol. So instead of trying to explain and use my shaky memory of this gym, have this instead: http://www.youtube.com/watch?v=LCCW9qi1Rjw
idk if you're playing DP or Platinum, but I don't think the gym changed for those games...the link is for the DP version though, if in fact they are different. If you're playing Platinum and it doesn't look the same, I guess just search for a Platinum one instead. Cheers.