1. Connect device via USB and make sure debugging is working, then run:
adb tcpip 5555
adb connect <DEVICE_IP_ADDRESS>:5555
2. Disconnect USB and proceed with wireless debugging.
3. When you're done and want to switch back to USB debugging, run:
adb -s <DEVICE_IP_ADDRESS>:5555
To find the IP address of your device, go to Settings > Wi-Fi > Advanced > IP Address on your device or run adb shell netcfg.
No root required. Only one device can be debugged at a time.
The adb command is located in the platform-tools folder of the Android SDK.