Routine for Changing The discount in pricing

hi all,

i am facing a problem in routines. i will describe what i have to achieve first. i have to write a routine to calculate the performance discount for a dealer in the billing.so i have created a routine under requirements->pricing(RV61A901) and wrote the code to calculate the performance discount for the dealer.the functional guy has attached my routine for the specific condition type too.now my routine will work only if the condtion type appears in billing(VF02). now i have to make the new calculated value come in the condition table(xkomv internal table) holding the values and rates for various conditions which should reflect in the billing again (VF02). how do i do it...pls advice...

regards

kiran