Well after more researching it seems that for whatever reason Steam itself is just broken. Game is also probably Steam-only.
http://www.runningwithscissors.com/postal-3-steam-keys
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Blue Cucco / Waiting Cactus
http://img355.imageshack.us/img355/4915/cojiro2nk2.jpg http://i53.tinypic.com/14wf59z.gif