i am looking for the exact same thing. I also figured out that we should combine the xcode syphon simple client and blackmagic openGl to output on their cards. Unfortunately i am not a programmer able to do this.
For the moment i use firewire out. I just tested in quartzcomposer to link syphon client and v002_DV plugin. This works with a bit of latency. From there i go true a xdcam recorder to convert to SDI.
anyway if you find a solution… let me know 😉