Hi Shiva,
Please go through the SDN before posting 
you will find many discusions .
http://scn.sap.com/thread/1843468
check below code in method do_config_determination. We made Account category default.
But according to your requirement , you need to check the account type and make the required role default.
CALL METHOD super->do_config_determination
* EXPORTING
* iv_first_time = ABAP_FALSE
.
DATA: lr_search TYPE REF TO cl_bsp_wd_value_node,
lr_shuffler_ent TYPE REF TO if_bol_bo_property_access,
lr_cuco_shuffler TYPE REF TO cl_bp_head__cucoshuffler,
lr_shuffler TYPE REF TO cl_bsp_wd_value_node.
IF iv_first_time = abap_true.
TRY.
lr_cuco_shuffler ?= me->get_custom_controller( 'BP_HEAD_SEARCH/CuCoShuffler' ).
CATCH cx_root.
ENDTRY.
IF lr_cuco_shuffler IS BOUND.
lr_shuffler ?= lr_cuco_shuffler->typed_context->search->collection_wrapper->get_current( ).
IF lr_shuffler IS BOUND.
lr_shuffler->set_property_as_string( iv_attr_name = 'CATEGORY'
iv_value = '2' ).
ENDIF.
ENDIF.
ENDIF.
* call super
super->do_config_determination( iv_first_time = iv_first_time ).
Thanks,
rama