So for each USB HC (EHCI, XHCI, OHCI, etc) that is needed you would need to implement the required isochronous transfer. This likely involves managing the DMA queue of the hardware.
You would also need a generic change to the USB Bus Driver to implement the UsbIo services on top of the Usb Host Controller services. That would work for every USB Host Controller.
Sorry I don’t know of any EFI USB Stack that implements Isochronous transfers.
Thanks,
Andrew Fish
PS FYI that post I sent about gdb should work for you too if you grab those 2 files.