OK, I'm nearly finished with the current project, so I allowed myself some play. Here's a first BG sketch over the grid just to see how it works. Load this into your AS 9.5, select "Script > Image > Spherical Panorama", select camera pan tool (7), play around. Hit cmd-J for nicer experience.
It works pretty fair in horizontal pans, but if you go to zenith or nadir you'll see the glitches. The room is a bit small for my taste, next time I'll do better. The lines of desk and floor are not 100% straight, but I think that's OK within this style.
The bookshelf in the back is something I did quite a while ago and re-used it already in different projects. Import the image into TVPaint and use the warp grid with some good resolution, I used 7 horizontal and 6 vertical points. Select columns of points first (marquee select) to shift horizontally in place. Then place the points so the connecting lines meet or follow the grid lines.
Maybe I'm a bit obsessed with the clear lines, a more painterly approach could be better. Looking forward what others do with this!