A device template needs to be created for this, with the child devices for each of the tuners and the capture ports. WE should also add the vendor/model id of the pci card so it's plug and play and gets auto-created (see the template for the PVR 250).
Then when you add a satellite box (wizard, devices, a/v equipment), you can specify which port on the capture card it's connected to. And for each satellite box you can also specify the usb->rs232 that's used.
This does work; I have a bunch of rs232-controlled a/v devices in my installation.
Are you in the U.S.? Can you send me an email to aaron.b, and perhaps we can setup a time when you're by the phone to talk, if you enable remote assistance I can login and get the data for the card, add it to the central database, and then it will work with the next release.