Hi Vijay,
CRM was inbuilt in ECC side. there is no specific steps to crm sap defined data sources extraction.
if you want specific data source flow please specify the data source name, that would better for us to suggest the required steps.
If your going to use SAP standard data sources, procedures are same we do for other standard data sources.
Like activating data sources from Tx - RSA5(ECC) and check data mechanism/records at RSA3, once we are confirmed that data was coming as expected. replicate data source into bw side and build a cube or dso.make transformations between data source and target, create info package and dtp.
Remaining bw steps are common loading full thru info pack and load data to target thru dtp.
run init without data transfer, run delta info pack and delta dtp.
Thanks