Single aircraft mods install the same way no matter what game version or modpack you have. First, you download the archive. Let's say you were installing the Me-264 by 101tfs.
I would then check which folder is the mod folder. The mod folder is the one full of gibberish files. The contents of this folder look like this:
This folder must be moved to your active mods folder, which, in B.A.T. 1.0, is called #WAW2.
You must then read the readme to check for other mods that you might need for your mod to work. The readme tells you this:
This means you must install the latest SAS common utils, which installs the same way as a plane mod (move the mod folder with all the gibberish files in it to the #WAW2 folder) except it also has a DLL which you must put in the main game folder (the folder with il2fb.exe in it).
Once you've moved the plane's mod folder to your mods folder and installed all the other mods it needs, you must then add the lines to the appropriate ini and properties files for the game to load the plane in.
You must memorize the locations of these three files:
#WAW2/STD/com/maddox/il2/objects/air.ini
#WAW2/STD/i18n/plane.properties
#WAW2/STD/i18n/weapons.properties
The mod's readme file will tell you which lines to add to which files. In this case, you must add
To your air.ini:
Me-264/4m/801E air.ME_264_4M_801E 2 NOINFO g01 SUMMER
To your plane.properties:
Me-264/4m/801E Messerschmitt Me-264/4m/BMW 801 E, 1944
To your weapons.properties:
#####################################################################
# Me-264/4m/801E
#####################################################################
Me-264/4m/801E.default Default
Me-264/4m/801E.default_boost RATO Boosters
Me-264/4m/801E.88xsc50 88x 50kg Bombs
Me-264/4m/801E.88xsc50_boost 88x 50kg Bombs + RATO
Me-264/4m/801E.72xsc50 72x 50kg Bombs
Me-264/4m/801E.72xsc50_boost 72x 50kg Bombs + RATO
Me-264/4m/801E.48xsc50 48x 50kg Bombs
Me-264/4m/801E.48xsc50_boost 48x 50kg Bombs + RATO
Me-264/4m/801E.24xsc50 24x 50kg Bombs
Me-264/4m/801E.24xsc50_boost 24x 50kg Bombs + RATO
Me-264/4m/801E.88xsc70 88x 70kg Bombs
Me-264/4m/801E.88xsc70_boost 88x 70kg Bombs + RATO
Me-264/4m/801E.72xsc70 72x 70kg Bombs
Me-264/4m/801E.72xsc70_boost 72x 70kg Bombs + RATO
Me-264/4m/801E.48xsc70 48x 70kg Bombs
Me-264/4m/801E.48xsc70_boost 48x 70kg Bombs + RATO
Me-264/4m/801E.24xsc70 24x 70kg Bombs
Me-264/4m/801E.24xsc70_boost 24x 70kg Bombs + RATO
Me-264/4m/801E.88xsc100it 88x 100kg Bombs
Me-264/4m/801E.88xsc100it_boost 88x 100kg Bombs + RATO
Me-264/4m/801E.72xsc100it 72x 100kg Bombs
Me-264/4m/801E.72xsc100it_boost 72x 100kg Bombs + RATO
Me-264/4m/801E.48xsc100it 48x 100kg Bombs
Me-264/4m/801E.48xsc100it_boost 48x 100kg Bombs + RATO
Me-264/4m/801E.24xsc100it 24x 100kg Bombs
Me-264/4m/801E.24xsc100it_boost 24x 100kg Bombs + RATO
Me-264/4m/801E.18xsc250 18x 250kg Bombs
Me-264/4m/801E.18xsc250_boost 18x 250kg Bombs + RATO
Me-264/4m/801E.9xsc250 9x 250kg Bombs
Me-264/4m/801E.9xsc250_boost 9x 250kg Bombs + RATO
Me-264/4m/801E.10xsc500 10x 500kg Bombs
Me-264/4m/801E.10xsc500_boost 10x 500kg Bombs + RATO
Me-264/4m/801E.6xsc500 6x 500kg Bombs
Me-264/4m/801E.6xsc500_boost 6x 500kg Bombs + RATO
Me-264/4m/801E.2xsc1000 2x 1000kg Bombs
Me-264/4m/801E.2xsc1000_boost 2x 1000kg Bombs + RATO
Me-264/4m/801E.1xsc1000 1x 1000kg Bomb
Me-264/4m/801E.1xsc1000_boost 1x 1000kg Bomb + RATO
Me-264/4m/801E.2xsc1800 2x 1800kg Bombs
Me-264/4m/801E.2xsc1800_boost 2x 1800kg Bombs + RATO
Me-264/4m/801E.1xsc1800 1x 1800kg Bomb
Me-264/4m/801E.1xsc1800_boost 1x 1800kg Bomb + RATO
Me-264/4m/801E.2xsc2000 2x 2000kg Bombs
Me-264/4m/801E.2xsc2000_boost 2x 2000kg Bombs + RATO
Me-264/4m/801E.1xsc2000 1x 2000kg Bomb
Me-264/4m/801E.1xsc2000_boost 1x 2000kg Bomb + RATO
Me-264/4m/801E.2xsc2500 2x 2500kg Bombs
Me-264/4m/801E.2xsc2500_boost 2x 2500kg Bombs + RATO
Me-264/4m/801E.1xsc2500 1x 2500kg Bomb
Me-264/4m/801E.1xsc2500_boost 1x 2500kg Bomb + RATO
Me-264/4m/801E.10xsd500 10x 500kg AP Bombs
Me-264/4m/801E.10xsd500_boost 10x 500kg AP Bombs + RATO
Me-264/4m/801E.6xsd500 6x 500kg AP Bombs
Me-264/4m/801E.6xsd500_boost 6x 500kg AP Bombs + RATO
Me-264/4m/801E.10xsd1000 10x 1000kg AP Bombs
Me-264/4m/801E.10xsd1000_boost 10x 1000kg AP Bombs + RATO
Me-264/4m/801E.6xsd1000 6x 1000kg AP Bombs
Me-264/4m/801E.6xsd1000_boost 6x 1000kg AP Bombs + RATO
Me-264/4m/801E.4xsd1000 4x 1000kg AP Bombs
Me-264/4m/801E.4xsd1000_boost 4x 1000kg AP Bombs + RATO
Me-264/4m/801E.2xsd1000 2x 1000kg AP Bombs
Me-264/4m/801E.2xsd1000_boost 2x 1000kg AP Bombs + RATO
Me-264/4m/801E.3xpc1600 3x 1600kg AP Bombs
Me-264/4m/801E.3xpc1600_boost 3x 1600kg AP Bombs + RATO
Me-264/4m/801E.2xpc1600 2x 1600kg AP Bombs
Me-264/4m/801E.2xpc1600_boost 2x 1600kg AP Bombs + RATO
Me-264/4m/801E.1xpc1600 1x 1600kg AP Bomb
Me-264/4m/801E.1xpc1600_boost 1x 1600kg AP Bomb + RATO
Me-264/4m/801E.18xab250 18x 250kg Bomblet Container
Me-264/4m/801E.18xab250_boost 18x 250kg Bomblet Container + RATO
Me-264/4m/801E.9xab250 9x 250kg Bomblet Container
Me-264/4m/801E.9xab250_boost 9x 250kg Bomblet Container + RATO
Me-264/4m/801E.10xab500 10x 500kg Bomblet Container
Me-264/4m/801E.10xab500_boost 10x 500kg Bomblet Container + RATO
Me-264/4m/801E.6xab500 8x 500kg Bomblet Container
Me-264/4m/801E.6xab500_boost 8x 500kg Bomblet Container + RATO
Me-264/4m/801E.2xab1000 2x 1000kg Bomblet Container
Me-264/4m/801E.2xab1000_boost 2x 1000kg Bomblet Container + RATO
Me-264/4m/801E.1xab1000 1x 1000kg Bomblet Container
Me-264/4m/801E.1xab1000_boost 1x 1000kg Bomblet Container + RATO
Me-264/4m/801E.2xsc1000+6xsc250 2x 1000kg + 6x 250kg Bombs
Me-264/4m/801E.2xsc1000+6xsc250_boost 2x 1000kg + 6x 250kg + RATO
Me-264/4m/801E.3xpc1600+5x2d500 3x 1600kg + 5x 500kg AP Bombs
Me-264/4m/801E.3xpc1600+5x2d500_boost 3x 1600kg + 5x 500kg AP Bombs + RATO
Me-264/4m/801E.2xab1000+6xab250 2x 1000kg + 6x 250kg Bomblet Container
Me-264/4m/801E.2xab1000+6xab250_boost 2x 1000kg + 6x 250kg Bomblet Container + RATO
Me-264/4m/801E.1xheisenberg Heisenberg Device (German Nuke, 11kT)
Me-264/4m/801E.1xheisenberg_boost Heisenberg Device + RATO
Me-264/4m/801E.1xheisenberg_para Heisenberg Device w/ retarder chute
Me-264/4m/801E.1xheisenberg_para_boost Heisenberg Device w/chute + RATO
Me-264/4m/801E.none_boost Empty + RATO
Me-264/4m/801E.none Empty
Once you have added all those lines to the appropriate files, you are done, and you may fly the new plane.
It seems complicated at first (it sure did to me), but once you've got it down, it will come to you like second nature.