Yeah the Stellarvue is a good to go, Its the IS version. What is your astrobin profile? Ill take a look
Please check my signature.
So this firmware hack sounds necessary. Are there good guides and is it something that can easily be done? I’m familiar with CHDK which is probably the Canon equivalent.
I wouldn't say it's necessary. If you are an expert already, you won't be satisfied with D800 images, and the hacked D800 images will make you very happy. On the other hand, if you are a beginner (I guess yes), you probably cannot tell what's the problem in the images produced by an unhacked D800. So you may simply start using your D800 and enjoy its amazing sensitivity without worrying about the hack. Just keep in mind that if one day you feel unsatisfied about D800's linearity, there is something that can turn D800 into a perfect camera.
I initially tried the RAM hack that had been released by NikonHacker but using it precluded the use of Backyard Nikon which I used for image acquisition. In some other thread here on CN I had asked if the firmware hack was compatible with BYN but didn't get an answer.
There is an official answer about this on BYN's own user support forum. And the answer is no, BYN will not support it. For my hacked D800, I use DigiCamControl. When I use it in unhacked mode, BYN works perfectly.