9x9 binning with STL-6303E?

I would like to use an SBIG STL-6303E camera for a transient observation on a larger telescope with a long focal length, and thus bin excessively to match our spatial sampling to the image size while also notably reducing readout time.

The SBIG "Research Series" cameras, which explicitly included the STL-6303E, were advertised in old SBIG catalogs to have software selectable binning modes of 1x1, 2x2, 3x3, 9x9, 1xN. For our use case, the 9x9 binning mode would be just perfect. I imagine readout times should scale with binning and thus be quite short.

We tried MaximDL v5 (the observatory running this camera does unfortunately not have a MaximDL v6 license, but I anticipate that later MaximDL versions have not made changes relevant to controlling cameras that old), which offers binning for this camera model only up to 3x3. We also tried SBIG's CCDOps v5, which offered us 3xN binning, but not 9x9. We have not tried it yet with CCDSoft - I have not installed nor used CCDSoft perhaps for ten years or more now, and we may need an old WinXP or Win7 machine to try it...

Before we dig any further, does the STL-6303E support 9x9 binning, or was this advertised but never implemented for this particular model? Do we experience a software / driver limitation or an actual camera firmware limitation? If the camera can do 9x9 binning, how could we get 9x9 binned images?

I understand this camera is quite old, but your input on this would be greatly appreciated!

Thank you very much -
Karsten Schindler