IM Back to *** Turn

Regarding the back to *** turn in the IM, is it legal to grab the wall or top of the gutter when turning? I find that grabbing the wall helps in pulling the legs into the wall in preparation for pushing off. I read the rules on the backstroke and IM and did not see anything prohibiting this, but want to make sure before developing a habit. Also, any advice on a better way of making the turn is welcomed.