If you have downloaded and installed Xcode to your computer and you don't want to pay Apple the $100 to test your application on your device or to submit it to Cydia, you can create a certificate to fool Xcode into allowing you to fully build and test your application.
The following steps will describe how to create this certificate, deploy it into Xcode, and a few steps on how to submit your application to Cydia once you're done creating it.
These steps are the same on a Mac or a virtual machine to run OS X.
1. Watch this video and follow it's instructions:
2.Once you've finished creating your app, Ctrl+Click the application's name and click on Get Info.
3. Navigate to the Full Path of the application, this is the file you will be submitting.
4. Go to http://modmyi.com/devportal and fill out all the details. They will email you once your package is in Cydia.