But if you read the instructions rather than rely on line numbers you will be fine. Take it slowly and read the read-me file line by line. Don't be in a rush.
If you have other mods, the lines could be all over the place. Look for the existing code, carefully read and then replace or add each bit one at a time. Old saying measure three times, cut once.
Oh and BACKUP before you do anything. If you get into trouble you can always restore that file from you backups.
Thats how I did it because of the same thing with the line numbers.