I don't know which version you want to install but I'll walk you through an example. It's a tad complicated so please follow my instructions carefully.
I downloaded the BOEING RC-135 CFM56 base pack & the RC135W 2006 - 62-4138 repaint for it
HERE.
First extract the base pack (HJG_Boeing_RC-135_CFM56_v5.zip) to a Temp folder. Open the extracted folder & find the folder named HJG_Boeing_RC-135_CFM56_v5 directly containing subfolders named model.RC135U_CFM, model.RC135W_CFM, Panel & Sound. Paste this folder into the FSX\SimObjects\airplanes folder.
Next extract the repainted textures (rc135w_usaf_2006_62-4138.zip) to a Temp folder. Open the extracted folder to find a folder named texture.rc135w_usaf_2006_62-4138. Paste this folder into the HJG_Boeing_RC-135_CFM56_v5 folder you previously installed to FSX.
Now you need to edit Aircraft.cfg for FSX to recognise the textures. First open the file named 'add to aircraft.txt' included with the repaint zip in Notepad. Copy the complete text & open Aircraft.cfg of your new aircraft in Notepad. Paste the text at the top of Aircraft.cfg below the first 3 lines of text. It should now look like this. (The new text is in Bold.)
// Add your [fltsim.xx] sections here.
// Remember to start with 0 (zero).
// Copyright Historic Jetliners Group. No uploading of HJG materials to any website without prior approval.
[fltsim.xx] // Change "xx" to next number in sequence starting from 0
title=Boeing/USAF RC-135W 62-4138
sim=RC-135_CFM
model=RC135W_CFM
panel=
sound=
texture=rc135w_usaf_2006_62-4138
checklists=
description=Boeing RC-135W Rivet Joint Circa 2006. This aicraft has been re-engined with CFM56 engines.
ui_manufacturer=Boeing
ui_type=RC-135W
ui_variation=Rivet Joint 62-4138 circa 2006
atc_heavy=1
atc_id=624138
atc_airline=Air Force
atc_flight_number=138[General]
performance=Length:
Thats awesome they even still have the old engines on the Combat Sent.
