This is hardly a tutorial but I know its harder for some people to reverse engineer other tutorials as well as other peoples work/problems to get a decent fix for a problem.
So this is just a small tutorial on some of the steps required for you to take to convert this UDK Game launcher tutorial into a UE4 one like I have.
This tutorial shows you the lines of code required to access and communicate with .ini files, IT also provides you with the project files so you can just tweak the existing tutorial.
However you will need to prepare your UE4 project correctly before doing this to allow access to .ini files after you Cook & Package.
[If you are having trouble Cooking and Packaging a BLUEPRINT ONLY PROJECT then read my tutorial on how to POSSIBLY fix it: https://answers.unrealengine.com/questions/104084/runuatbat-error-blueprint-project.html#answer-104696]
You will need to do as the answer says in this thread : https://answers.unrealengine.com/questions/74669/graphics-settings-for-packaged-game.html
Which is to create an .ini file called DefaultGameUserSettings.ini and place it in the “Your Project > Config” directory and recook/package the project.
Once you successfully manage to COOK & PACKAGE your project and LAUNCH IT FOR THE FIRST TIME you should now notice a new folder called SAVED navigate to “Config > WindowsNoEditor” and you will find your .ini files to edit.
From here its a case of using the information taught to you in the above tutorial to change directory paths and SettingsGroups accordingly to change your settings before the Project boots up.
Above is a shot of the Launcher I made using the same tutorial and currently works perfectly.
P.S. Be aware that i have not tested this on any other Packaging types, e.g: Windows or WindowsClient
These change directory pathing so you will need to look out for this especially with x32 and x64 packaging.
I can only guarantee this will work with a WindowsNoEditor packaging system.
Best of Luck
Please let me know if this was useful or useless
Or if you want a more in-depth tutorial creating a UE4 launcher