I tend to whip into the direction I'm trying to go while pressing that direction on the control stick. Have you tried recalibrating, checking the battery life, and all of that? Wiimote controls seem to get less accurate when the batteries are low.
You need to be moving in the direction you want to go and then just shake the remote however. It's straight up waggle, like they normally assigned the nun-chuck in this game. Punch, swing, stab, shake, it doesn't matter what the motion is. It's like using the jump button while climbing in God of War.
Keep in mind that you can't leap while hanging on a ledge when you encounter an edge. If the orientation of the ledge you're hanging on changes (for example, in Lanayru Desert when you're leaping to get to the color wheel near the entrance), you can't leap across those edges. You can only leap if you're climbing along a straight line.
Not sure if that explanation makes any sense. It took me awhile to figure this stuff out.