[AT&T Samsung Galaxy S 4 Q&A, Help & Troubleshootin] Nick.Lopez:
I don't take credit for anything on this post. It has all been information gathered from XDA.

I am by no means an expert and I have learned a ton from these forums so I wanted to give contribute.

This is a step by step guide of the instructions I followed to be able to install ROMS for newer people who might know enough to get themselves in trouble (like myself :D )

I tried to put as many details as I could remember to put down. If any of the more experienced members see anything wrong please feel free to correct me. I couldn't find anything that it says its against the rules so if it is Mods please excuse me and delete this post.

Yay my first post on XDA

YOU MUST ALREADY HAVE ROOT ACCESS - THIS DOES NOT ADDRESS THAT PART AT ALL

Step 1: Download Safestrap-JFLTEATT-3.6d-B09.apk (or latest -check the first post to make sure these instructions are still up to date) and jflt-MF3-Modules.zip file on to your micro SD Card. The Safestrap-JFLEATT file may try to download as a zip file make sure to rename it .apk (At least that's how I got to work for me)

Step 2: Go to Settings, More, Security and click Allow installation of apps from sources other than the Play store.

Step 3: Find a rom you want to install and save it to your SD card (should be a .zip file)

Do this before you start the rest of the processes below if this is your first time doing this! Trust me it will help!

***********You can actually flash any "jelly bean touchwiz only 4.2.2" rom on your virtual slot...doesn't have to be "mf3 stock kernel/rom" if example: I'm using Omega Rom from the i9505 forums...that isn't mf3 base...all you have to make sure to do is flash the kernel module patch immediately after flashing rom. You can flash from galaxy s4 verizon tmobile sprint & i9505 NOT i9500 ... But most likely you would have to input att LTE apn settings and select lte/gsm network mode if you are using a rom other than at&t roms... (thanks sykoj82 for the clarification) You can go to the Rom's section on xda to see what they have. Do this before you start the rest of the processes below if this is your first time doing this! Trust me it will help!

Step 4: Go to My Files app then navigate to your SD card and install Safestrap-B09.apk file.

Step 5: Go to your apps and click on the Safestrap and grant it SU powers.

Step 6: Click on Install Recovery.

Step 7: (I believe the phone will automatically reboot into recovery) but if not click reboot to recovery.

Step 8: After phone boots into Safestrap click on Boot Options and then on ROM-Slot1 --------------------------------------------Super important that you never install or wipe anything on STOCKROM (these options should be in red)

Step 9: Select partition you want to allocate for that particular slot - (I did 3gb) This should take about 3-5 minutes

Step 10: System will return you to the 5 roms page, select the back key.

Step 11: From your SD card select the name of the rom you want to install (from step 3)

Step 12: Swipe to confirm flash (this should take about 3-4 minutes) and should reboot (you will see Safestrap menu - click on recovery then click on install and select jflteatt-mf3-module.zip)

Step 13: The system will reboot and you will see the Safestrap animation guy - don't click anything - then you should see the Animation screen for your ROM - it may take a few minutes for it to load the first time.

Step 14: Enjoy your ROM courtesy of the many wonderful people at XDA who took their time to create and test this!