I have successfully used this method :
"To install this aircraft manually, copy the following text into your 'aircraft.cfg', inside the folder 'SimObjects\Airplanes\Aerosoft A319 IAE Professional'.
Replace the X in [FLTSIM.X] by the next following number (like [FLTSIM.8]) and put the snippet after the last FLTSIM-object.
Then you copy the complete texture folder into the same aircraft folder where you find the aircraft.cfg.
title = Airbus A319 British Airways G-EUPS
sim = A319IAE
model = GDBCF
texture = British Airways G-EUPS
kb_checklists = AirbusA321_check
kb_reference = AirbusA321_ref
atc_id = G-EUPS
atc_airline = SPEEDBIRD
atc_flight_number = 1000
ui_manufacturer = Airbus
ui_type = A319-131 IAE
ui_variation = British Airways
ui_typerole = Commercial Airliner
ui_createdby = Aerosoft
atc_parking_types = GATE,RAMP
atc_parking_codes = BAW
description = Airbus A319 - 131 IAE / British Airways G-EUPS \nwww.aerosoft.com \nRepaint by Holgi (simtexture.de)
I did the above and this aircraft appeared in the new Livery Installer under A319 IAE