Friendly fire must be off for this strategy to work. If you are the Rebels, start at the Temple as a Rebel Soldier. Take a speeder bike across the viaduct and go off the edge. You will be located on the river, right below the Outlook. Go up the hill to the Outlook. There will be loads of Imperials, so cut them down with your blaster rifle. The command post will take a long time to take, though, so be patient and cut down any Imperials that show up. Once you have taken the command post, you can attack on both sides of the Imperials, as well as cut off their AT-ST supply.