This aims to solve the annoying task of setting the bones between both skeletons to match each others one by one in non user-friendly dropdowns.
You can retarget from within the Unreal Engine editor and save the bone “configuration” for future skeletons, but in some cases that would be a hard to track file (may be lost in one of many projects) and may not be a good solution if you want to manually edit an skeletonand then retarget It.
This MaxScript will modify all the bone names to fit the ones UE4 human uses in just one click, adding the extra root bone mandatory by UE
Licensed under: Creative Commons: Attribution-NonCommercial-ShareAlike
Hierarchy BEFORE usage
Hierarchy AFTER usage
Using this plugin still requires you to retarget the skeleton In-Engine, but they will auto-fill all the correspondency between bones automatically so you don’t need to do anything by hand.