Well, I personally would use imaging lingo to complete this. To do this look up 'copyPixels'
Another way (one I have personally never done) is to cut your image up into small parts (much like you did but even smaller). I would guess 200x200 squares are ok perhaps 400x400. What ever you chose. Set your Stage to the large image WxH (so 3000x3000). Place all your pieces so they look like the one big image. Now this is the key, make a flim loop out of all those sprites. Delete your setup sprite tiles and just use the Film Loop.
The benefits here:
1) Imaging Lingo not required for those non programmer types
2) All you have to move around is the film loop rather than 100 or so sprites.
3) Director only has to keep 9 or so 200x200 images in memory and push them around rather than a single 3000x3000 image. Director unloads any of the tiles that are not visible on Stage so it does a lot of memory management for you.
Hope this helps
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