How do specify a dynamic range selection in scripting

How can I modify this script to do a dynamic range selection:
def itemSize = |HC Casual Labour Budget Input::’2′..Row|
I want to replace the ‘2’ in the first line to something that means the second item of a category Row no matter what the name of the second item is. I wish I could do something like:
def itemSize = |HC Casual Labour Budget Input::Row[FIRST+1]..Row|   so that it always selects from second row to the last row of the specified Row category.
Any help please