Since the laptop I use has a built-in bluetooth usb "stick" with broadcom chip (which doesn't work with btsco), I came to the idea that I could add another bluetooth usb stick and use that instead.
Other than the hcitools and so on there seems to be no way to tell the btsco tools which hci device to use (e.g. hci1 instead of hci0).
Neither does deactivating hci0 make btsco use the second bluetooth device.
It would be good if one could just specify which hci interface btsco should use to connect.