image pyramid viewing software

[Greg Coats]

For 100 large metropolitan areas, I have created separate reduced- 
resolution GeoTIFF images at 120, 60, 30, 15, 7.5, 3.75, and 1.875  
meters resolution.  I want to be able to zoom in, zoom out, and pan  
through this imagery, and have MapServer display's at any given time  
be from the GeoTIFF that is most appropriate, based on the current  
zoom.  How can this be done with MapServer?
Greg