Command your armory to supply the gun towers with the Mag cannon (1 Mag cannon if it is a NSDF gun tower and 2 Mag cannons if it is a CCA gun tower). They can track you, but only fire a small amount which can be seen at a distance.
Note: A tank equipped with two SP-Stabbers is required for this trick. First, use the hills for cover and wait for the Walker. Then, when it is close, run and jump and hit it while firing. If you are lucky enough, the Walker will fall. Once on the ground, the Walker will quickly try getting up again -- waste no time in killing it. When the Walker is on the ground, it cannot shoot you. Another technique is to use the thumper device on Walkers. They will be spinning around so quickly that they become easy tank fodder.
Start the game with the /edit command line parameter. Aprompt to use the mission editor will appear before the main menu appears, . After confirming your choice and starting the game, press CTRL + E to access the editor.