Just create or use a file of same structure than INDX, don't export to memory but to this database with EXPORT TO DATABASE statement, and give the key/id of the export to the transaction parameter shortcut, you can concatenate other (short) information to the parameter, the called transaction if required, this transaction will execute the IMPORT FROM DATABASE statement.
Sample Caller
EXPORT tcode FROM lv_tcode bdcdara FROM lt_bdcdata TO DATABASE zindx(bc) ID lv_id.
Sample in called
IMPORT tcode TO lv_tcode bdcdata TO lt_bdcdata FROM DATABASE zindx(bc) ID lv_id. CALL TRANSACTION lv_tcode USING lt_bdcdata.
Regards,
Raymond