You might be able to get close with \i as your replacement which will allow it to count what replacement it is on. It won't take a formatting operation though so you wouldn't get the preceding 0 and if numbering doesn't start at 1 then you'd have to do a special case of 0.
It doesn't sound like that applies here but for future users searching the boards, if you are attempting to address columns of an array 0-x, be aware that you'd need to hand code the 0 and \i would catch the 1-x case.
