If you are wobbling back and forth it is probably not steering but a lumpy peadling stroke. Have you ever done any isolated leg drills? This will identify the weak spots in your stroke. Rollers are the best way to develop an even stroke because if you don't you will fall off on your head. I have never been bored on rollers, terrified is more like it. Demands constant concentration. But produces results instantly. If you just can't steer a stright line you might just neeed to relax a bit, but maintain concentration on what you are doing.