Move selected polys in order (arrgh can't delete double post)

I wanted to make stairs more easy to do.
I usually draw the stair on top view with one editable poly.
Then I select polys and move up or down one by one...
It is nice because it works on all type of stairs I need.
What I want to do is select polys in order ( paintselect ) and run script to move first poly 10cm up, second poly 20cm up,....

Anybody can help ? Thanks.