Hi Suneel,
One of the method to conversion is using LSMW
first extract the data from your table ZXXXX - (ECC5) to excel file
then Record SM30 maintenance for one entry of your Z-table (ECC6), incl. saving the data and returning to the SM30 entry screen. This recording is the basis for your LSMW object that you will have to build and that will read the entries from your Excel list and insert them into your Z-table.