Reduce damage while retreating:
Set the combat mode option to "Long" from the preferences screen. When attacked, quickly press R repeatedly to retreat with little damage.

Mission select:
Hold L + B + X + Y at the scenario map with the jeep. While holding those buttons, release X, then press X. Release all buttons and move the jeep to a dimmed area.. Press L + B to select this area.

CPU vs. CPU:
Position the jeep on a dimmed area on the scenario map. Hold Select, then press X.