Its comparable easy to set up. You need to run the SwarmCoordinator on your initial PC and the SwarmAgent on your render slaves and tell the coordinator to use your slaves via IP. Check out this documentation for UDK, it works identical for the UE4:
http://udn.epicgames.com/Three/DevelopmentKitContentCreation.html#Swarm%20Setup
And here is another tutorial with a better step-by-step explanation plus pictures:
http://www.froyok.fr/tuto_swarm_en.html
You’ll find both executables under \Unreal Engine\4.X\Engine\Binaries\