I'd love to know what parameters you're using in SCSI2SD to get this working.
I don't have my system up at the moment, but I seem to remember using default on the SCSI2SD to make it work. I would try all kinds of combinations before the SD card combination suggested in my photos. Then it worked with just the defaults, and I stopped trying anything else.
Also, regarding HQ6. I have the Millenium software package that includes many tools and add-ons written for the Flyer. One included a digitizer that allowed for the selection of HQ6. I tried a capture with it, but I got scrambled video (with audio if I remember correctly). So, I just assumed maybe my board couldn't handle it. Perhaps it can and maybe my SD card setup isn't fast enough. Would be great to find out more.
Cheers,
Greg