where should i include the copied payment advice script ?

Hi experts,

i copied script from std script form (F110_IN_AVIS) . I did some modifications ,now i want to include this script name

(my form name is YPM_F110_IN_AVIS)

in the program.Where should i include (in f110 or somewhere) my script so that when executing the tcode FCH7

modified script will be executed.please give me the steps.pls help me in this.