I found this manual at http://ouyaforum.com/showthread.php?2752-How-to-Pair-a-PS3-Controller-with-OUYA and I give a full quote because I fear forum entries are lost over time:
“This guide is intended to guide you through the steps needed to connect your Playstation 3 Dual Shock Bluetooth Wireless controller to your OUYA.
It should be noted that not all OUYA games support the PS3 controller. However, it should allow you at a minimum to navigate the OUYA menu
1. Turn your OUYA on and make sure you have at least one OUYA controller paired
2. Plug your PS3 Controller into your OUYA using a mini-USB to standard USB cable
3. Hold down the home button on your PS3 controller. This should take you back to the OUYA home screen. Make sure the PS3 controller is working by using it to navigate the menus. You will also note that the OUYA controller has been disconnected and won’t pair. This is because plugging in the PS3 controller on USB turns off bluetooth.
4. To solve this, first completely power down your OUYA. You can do this by either holding down the power button on the top of the console for 5 seconds (recommended) or unplugging the power cable.
5. Unplug the PS3 controller from the mini-USB wire, and unplug the same wire from the OUYA.
6. Turn the OUYA back on. When it finishes booting up, you should see the usual pairing screen appear
7. Hold down the home button on the PS3 controller as you would with a normal OUYA controller to pair it. Other OUYA controllers should now also pair”
I haven’t tried this yet due to lack of PS3 controllers.