Basic breakdown of how to retarget Jess from ESRPG to the UE4 skeleton. This is just a basic example and can be improved by further refining the positions/settings.
Should work for any skeleton although the closer in size to Jess the better.
0:00 Rig for Jess
3:00 Rig for UE4 Manny
4:35 Retargeter
10:50 Retarget ABP
14:40 Add Sockets
15:40 Melee Animations
19:10 Rifle Animations
26:30 Bow Animations