Getting all the maps along the border of a seam in the terraserver maps (like 90 degree longitude) is time consuming because the 90 degree line isn't exactly vertical, and if any part of the rectangle crosses the line then it returns a zero set. Thus, the best way I've found to get all the maps is to move up and down the line defining very small sections to import.

One fix I can think of is if you could define the download range rectangle by GPS co-ordinates, like "90.00 W 35.00 N to 90.50 W 36.00 N".

Even better, but maybe not possible, would be to allow the defining rectangle to cross the seam line without returning a zero set.