I created a blog post that shows ALL of the steps that you need to do to port your existing game to OUYA. This should demystify the process and save a lot of people from headaches in the future.
It doesn't say HOW to make the actual game, but if you want to use the OUYA mouse as your control device, you can follow this guide and start playing your application on OUYA.
The guide's process begins at downloading the needed SDKs and ends at exporting the finished application. It also explains how to actually get your game onto the OUYA in the easiest possible way with FilePWN.