code for Bex reporting enhancement

Hi to all,

i had a query in BEx reporting enhancement where i have to write the code .

could anyone explain in real time scenario,with example taking processing type as customer exit(if possible a code for enhancement) and what varaible type is preferrable ?

could anyone give some points how exactly the interaction between client and the bw consultant ? what are the tasks to be done for the client?

thanks in advance ...

bye,

sekhar