Hi Jagadeesh,
if you have standard hierarchy data source then you can use it and load data from ecc to bw related info object. the same info object can be used at info level. thru star schema concept when you use primary info object at cube, at bex level we can sue related hierarchy structure.
Seems like you may dont' have standard one. you can go for flat file hierarchy data source and load it.
creation of flat file hierarchy you can check above links shared by suman.
Thanks