No, don't reverse the wires. If you don't want to use the switch (and I'd love to know why), you can buy pretty inexpensive servo reversers that connect inline with the servo. Most of the time people buy these to hang two servos off the same channel and reverse one of them, such as for aileron operation. The reason you can't reverrse the wires is that the positive and negative wires do not go directly to the motor, they power a circuit which then powers the motor. So by reversing the wires, you would by feeding reverse polarity into this circuit. Usually this won't harm anything, but it also will not work.

Here are some reversers you can buy...

[link=http://www.aeromicro.com/Catalog/dionysus_design_servo_reverser_3975198.htm]Dionysus Design Servo Reverser - $9.95[/link]
[link=http://www.fmadirect.com/Detail.htm?item=1398&section=61]FMA Direct Servor Reverser - $16.95[/link]

There are many others if you look around, some are integrated into a Y-harness for the aileron operation. Good luck.

Dave