OK, first things first. If you are not already rooted, follow the first link to get Framaroot. Install and run it using the Aragorn option. This will give you permanent root and install superuser.
Now use the second link to get the GB27 sxtp .tar recovery(Sprint), I would recommend the latest version. I have used the same one on my Virgin Mobile E4GT without problems. While you're there, I suggest you also download the GC01 stock restore .exe. This is a one click self extracting Odin zip file to restore your phone to factory, in case of any mistakes (this is used on your pc). Also, if you're looking to install any CM or AOSP roms you will also need to get the ICS modem. You can find both the ICS and JB modems for Boost there. I would suggest the zip file flashable in your recovery.
If you want one of the 4.4.2 roms such as Vanir, Commotio, Villuminati, or CM11, then you will also need the Blasphemy kernel. Flash it in recovery, reboot into your new recovery then flash the rom and gapps.
Once you get rooted, the files downloaded and on your phone, use Mobile Odin to flash the GB27 kernel. Once your phone reboots you will have a custom recovery. The first thing you need to do is reboot into recovery (power off, then hold the volume up and power buttons until it boots into the recovery), then make a backup of your system. You can restore this if you have any problems down the road.
If you're looking for the largest selection of roms, I would recommend you visit the Epic 4g Touch Forum on xda-developers. They have the widest variety of roms ranging from stock TouchWiz based roms to the latest Kit Kat roms. Just remember to follow the developers instructions for flashing and installing any rom or modification.
As always, I accept no responsibility for any damage to your device. Any changes or modifications you make, are your sole responsibility and you do this at your own risk.
Happy Flashing
[ROOT] Framaroot, a one-click apk to root some devices - xda-developers
Rwilco12's Android Repository
[2014.03.22][ROOT] Mobile ODIN v4.10 - xda-developers
[Kernel][3.0.101][OC/UV] Blasphemy Kernel v6.6 - xda-developers