The implementation of this is available here: shapespark-viewer-api/body-end.html at master · shapespark/shapespark-viewer-api · GitHub
To place it in the bottom change: top: 0px; into bottom: 0px;.
Using a hand drawn floor plan should be possible, it was discussed here: Location on a plant map - #2 by jan, but I’m not aware if anyone actually did it. Also here: Floor plans with extensions? - #4 by wojtek Wojtek suggests to try LayOut in SketchUp to generate floor plan images.