How can i change a row number ??

I would like to change a row number folowing the next example;
if cur_row=current row i woud like to have the value: cur_row=cur_row+k;where k is a number;
Thank YOU... excuse me for my bad english

obj.setRowText(function(i){return i + k});

Where to Place?

obj.setRowText(function(i){return i + k});
Where it will be executed?