Add the following to your map (I used wallofslaughter_1.txt):
P -477, -56, 2, 0, 240, 240, 3, D
P -480, -209, 2, 0, 240, 240, 3, D
P -644, -58, 2, 0, 240, 240, 3, D
P -2032, -546, 154, 0, 240, 240, 3, D
P -1999, -407, 161, 0, 240, 240, 3, D
P -2500, -129, 45, 0, 240, 240, 3, D
P -2295, -549, 38, 0, 240, 240, 3, D
P -637, -227, 2, 0, 240, 240, 3, D
P -2176, -597, 36, 0, 240, 240, 3, D
P -497, 230, 62, 0, 240, 240, 3, D