2006 lly, trying to adjust speedo by -2mph. When i go into speedo fine tuning, it gives me a correction of 0.967742

where do i input this calculation? Do I add it to the original calculation?

When I do the shift point correction, im assuming that I just input the 0.967742 into the adjust by box do I also have to change something in the tcm?

Thanks in advance...
Tim