USEREXIT to adjust the rebate credit memo request to your own require

We are using function module SD_BONUS_CREDIT_NOTE_CREATE in one of our rebate program.

This Functional provides the option to use USEREXIT to adjust the rebate credit memo request to your own requirements.

With Present form of functionl module it take standard doc type to create the rebate credit memo request.

So Question here which are userexit we have in this FM which can be used to create the rebate credit memo request to our requirement.

Has any body used this FM before to this length..

appreacite your help

Thanks

rao