First I would like to thank the NSD team for allowing patches to be installed in such a way that it allows you to be backward compatible meaning allowing you to install an earlier patch over the most current version (installing version 1.2 over 1.3, etc).
Okay if you already have JSGME (Mod Manager) then go to step one. If you DO NOT have JSGME I strongly suggest that you download it. If you don't want to download, and install it then continue on your way quietly to another post on the forum because this is not for you. :blink:
JSGME Download: http://www.justallinone.com/files/jsgme_setup.exe
Step #1: Install JSGME. When it asks where to install itself make sure it points to your Scourge of War Directory... eg. <drive letter>:\NorbSoftDev\Scourge of War - Gettysburg (SOWgb's standard installation path).
Cool Tip #1: You can have as many JSGME installs on your computer as you want too, there is no need to uninstall it.
Step #2: Start JSGME. Now this is important, when JSGME asks what you like to use as a MOD Folder, DON'T select the default which is MODS. The MODS directory is SOWgb's, and SOW's folder only, so enter something like JSGME (makes it's easier on the head, and less confusing). Now if JSGME says the directory is not found, just create the JSGME directory in your SOWgb game folder (use windows explorer, or something similar. {I use Free Commander, great util).
Step #3: Okay you have installed JSGME, and you told JSGME where your mods will be found....Excellent!!!
Cool Tip #2: Backup your keyboard.csv file (this file has all your cool keys you use while you play the game).
Step #4: We will be using the latest Beta patch NSD has released to get you going. Okay double click on the beta patch 1.4 for SOWgb. Now start the install it will ask you where to install it. It always chooses the path to the game....WAIT...Read the Notices below.
IMPORTANT NOTICE #1: DO NOT choose your Scourge of War - Gettysburg path, instead choose something like C:\temp or D:\temp something along those lines.
IMPORTANT NOTICE #2: when it finishes the install DO NOT choose Run Scourge of War - Gettysburg. Deselect that option, and exit or press finish whatever it says to do. :blink:
Whew, close one huh? Was for me... :huh: I get mouse happy when trying something new which has always gotten me into trouble.
Step #5: For this example we have just installed version 1.4 of SOW in a temp directory. Now find where version 1.3.010 of SOW, and install. It will ask where to install it, and it will have the path of where you just installed patch version 1.4 which is WRONG. Select the browse option, and make sure you select your Scourge of War - Gettysburg game directory which is normally <drive letter>:\NorbSoftDev\Scourge of War - Gettysburg.
INSTALL IT!!!
You can start the game, but there isn't any point right now, we should be focused on getting the mod installed...up to you though. If you need to congratulate yourself then go ahead, play a game to clear your head...I'll wait! 
Step #6: Alright now we are almost home free, this is where it gets easy. Make your way to your JSGME mod directory is. Now create a directory called something like Scourge of War - Gettysburg 1.4
Step #7: Okay with that done make your way over to where you installed patch 1.4. Copy or move all those files in that directory over to your new directory you made in Step #6.
Step #8: Start JSGME.
Step #9: When you are ready you will see Scourge of War - Gettysburg 1.4 in the left panel. The left panel shows you what mods you can choose from which have not been activated yet.
Step #10: Highlight Scourge of War - Gettysburg 1.4, and select the arrow pointing to your right to activate it (give JSGME a few seconds to copy the files, and do the proper backups of your game). When you want to deactivate the game patch just highlight Scourge of War - Gettysburg 1.4 found your your right, and select the left arrow button.
Cool Tip #3: While you have the patch mod version active, to keep all of your settings just copy your SOWgb.ini from your <drive letter>:\NorbSoftDev\Scourge of War - Gettysburg\Work directory to your Scourge of War - Gettysburg mod work directory.
Standard Disclaimer: Please remember I only post this because I like to give a helping hand to those who wish to go that extra step. You can shake your fist at me, and call me names which is okay because I'm pretty sure I have called myself those very same names...