I did some investigating, and the variation in asset size and the almost infinite set of possible positions for objects within a hex tile mean that it'd be very, very hard to make this stuff HexKit compatible.
Perhaps you could create readymade custom hex tiles made up of these assets, in many variations — for each selected tile type, HexTile paints with random instances of the variations within each folder — but even if you did that, at HexTile's resolution, a lot of the detail would be lost.
I think HexKit and this amazing set of wonders are working at two different scales.