@INC is global to the script you are using - one script. You will have to edit each of the scripts you are refering (sic) to . . . sounds like a job for . . . Perl!

script to edit multiple files and add said 
line left as exercise to the reader 
          
                  >:)
[download]

Jeff

R-R-R--R-R-R--R-R-R--R-R-R--R-R-R--
L-L--L-L--L-L--L-L--L-L--L-L--L-L--