The best way to to use those little black and white sections on the guide rods mounted on the grill. You will need to practice and practice.
Since HTC updated the damage of those rockets, I have not seen many players use them. Too bad, really. Im not exactly sure how the splash damage has been effected if at all, but the new damage is 280 lbs worth (up from 234 lbs). It takes 312 lbs to take down the basic OBJ (building, ammo bunkers, fuel tanks, barracks, radar, factory, etc).