Sorry, don't know about any scripts. If you are good at tinkering or know someone who is, there are two relatively straightforward hardware methods that don't interfere with any cheat protection:
1) Open up the keyboard and attach a switch to the "w" key pins from the underside. If you use a double-switch, you can have the shift button pressed as well. The switch can be attached to the keyboard by drilling a hole where there is enough space for the switch enclosure on the inside of the keyboard.
2) More fancy would be an arduino that acts like a keyboard. It could have multiple functions, like with or without shift, a speak button, .... (I use this method with a self-built foot pedal as teamspeak push button. Software is trivial and open source, I can post relevant links if you want to do this).