Just days after the release of ChevronWP7 , The first homebrew app (along with full source code) for Windows Phone 7 has just been released ! .
you can now download the ChevronWP7 custom ringtone manager now, The program is a .XAP (pronounced “zap”) file and can be deployed using the Microsoft “Application Deployment” tool with the Windows Phone 7 Developer SDK.
They are two parts to it. What you basically do is that you run the desktop app on your PC, select up to 5 WMA files of your choice, and then hit “Build ringtone XAP” button which will create a custom .XAP package. You will then have to simply deploy this package to your device to install custom ringtones on your phone.
You will of course first need to unlock your phone with ChevronWP7 in order to install custom ringtones via ChevronWP7 Custom Ringtone Manager.