There are three spouts on the pad which throw you in the opposite direction from where you contact them.
If you run at the pad straight on from the Huttball mound, it will always send you flying straight back from where you came. If you circle around it and approach one of the rear spouts from an angle, it will shoot you onto the ledge.
Here's a pic. (best I could find)
http://imageshack.us/photo/my-images/143/obstaclejumppad.png/sr=1
You can get an idea from that where it will send you based on where you come in contact with the spouts.
If it's still sending you random places, latency might also be an issue.