you can check my blogs LSMW Material master by BAPI method - Part 1
and LSMW migration with IDOC method and using IDOC as source Part2: Import
to see how the Idoc method is activated and how the mapping is done, most steps in LSMW are equal
you can check my blogs LSMW Material master by BAPI method - Part 1
and LSMW migration with IDOC method and using IDOC as source Part2: Import
to see how the Idoc method is activated and how the mapping is done, most steps in LSMW are equal