I think what you want would have been this:
https://www.youtube.com/watch?v=qELcbKXdRm8
which is showing our CWBP map here - but since I stopped selling it and its unavailable from lack of interest, I would suggest:
Worldwind, GeoServer, GoogleEarth with custom skins, I believe that MapTool can do some zooming too.
Some comments about previous posts. Doing it by hand in HTML is a total pain. ImageMagick is great but it is not fast. There are apps to chop up large images into 2^n sized chunks for apps like the google maps services. Remember tho that any image you chop up cant then be changed so you need to do it all over again for every new bit of it that changes. Its also very hard to embed a small new map onto a regional or global map. You would have to use a paint program and do it at the exact resolution required. Also note that it fixes the pixels per meter ratio so that cities on a 64,000 pixel world would have to be rendered at 100x100 pixels or so. Completely useless. I.e. its not a path I would recommend.
If your really brave then you can have a go with Outerra and do it in 3D with sketchup...