There is no such thing as an "iTouch." The correct name is "iPod touch." That's like saying, "I drive a BMC!" when you really mean "BMW."
You must use a cable to synchronize music from iTunes to the iPod. If you're using a wireless network on the iPod touch, you can purchase and download music from the iTunes music store directly to the iPod touch, which will be copied to your iTunes library when you synchronize with iTunes again.
If you're looking to get music from iTunes on your computer to your iPod touch, then you must use the included USB cable.