I've transferred projects from Pro Tools to Sonar and also from Sonar projects into a fresh Sonar project, and there really isn't any quick way of doing it. You just have to roll up your sleeves and buckle-to.
In the end though, I think it's an easier process than you think it's going to be. I've transferred large MIDI projects which involved recreating synths and large FX chains from scratch. Sometimes you just have to get a pen and paper and make notes. But you can save synth/FX settings as presets - it's always good to save all of your presets in the project folder as you work anyway.
As for audio and MIDI clips I just take each track in turn. Bounce all the clips of one track into a single clip and make sure to extend the start of the clip all the way to the beginning so that you can position it easily in the new project.
I've actually enjoyed doing it. It's nice to recreate a project like this and feel like you're making a fresh start. It also forces you to look at the old project in great detail, which may lead to a bit of "spring cleaning" in the process.