Boy it's been along time, but I think I use to do it this way...
Lets say you have a background you want to scroll that is 3 "screens" wide. So lets say you have 3 different 320x200 image background, maybe a desert, then mountains, then a grass background.
You take the first background and move it on the X axis until it moves off the screen, lets say 30 frames. Now you take the 2nd background as a brush and follow the 1 st background on the right hand edge through those 30 frames. That way right at frame 30 the 2nd background is centered and filling the whole screen.
Repeat this, moving the 2nd background along the X axis until it's off the screen, from frame 30 to 60. Take the 3rd background as a brush and follow the 2nd one as it moves off the the screen.
You sort of stitch it together. You of course want to paint the backgrounds so they sort of blend into each other.
That doesn't make any sense at all does it? ;-)
