Given that Beckhoff's TwinCAT 2 and 3 - both free downloads - allow just that, and much more, I don't really see the point. Heck, anything that uses the realtime CODESYS stack allows you to do that, it's just that I know of TwinCAT. All those old Dell machines you may have hanging around can be great PLCs. Heck, the PLC (61131) libraries include functions that access hardware ports directly from realtime code, so you can bit-bang your parallel port with 1-2 microsecond jitter, if you wish so.
Best thing? It runs on top of standard Windows (XP or 7).
IOW, if you value your time, you won't care about such hacks. If you really want to run 61131 languages on bare metal, just get your CODESYS license, use an existing BSP or write your own, and you'll be set.