hello Vinayak,
My understanding here for mainframe as a source - DB2 would the probable database there, so by making DB2 connection in your datastore you can read the data.
I am also trying to understand for making CRM, APO, EWM as target that how to push the dat to them, lets wait for some inputs.
But feeling here is that it would be IDOC/BAPI methods through which BODS will push the data and target will get.
Best !
Deep.