2 sliderbars control, 9 images

I am trying to figure out how I can control 9 different background images with 2 smooth moving sliderbars in three steps with actionscript. :sigh:

Scenario:

slider 1, step 1 + slider 2, step 1 = picture 1
slider 1, step 1 + slider 2, step 2 = picture 2
slider 1, step 1 + slider 2, step 3 = picture 3
slider 1, step 2 + slider 2, step 1 = picture 4…

Anyone got a clue?:sigh: