As a ready to use out of the box IK solver no UE4 does not have this available except for the 2 bone solution that has “some” abilities built in but not at the same level of complexity as 3ds Max or Maya or even Blender.
But
You do have access to some basic constraint solutions or can make your own that duplicates some of the more common drag and drop constraints available in most if not all 3d applications that supports custom rigging requirements.
Some of the basics.
What is an IK solver.
As you see IK is IK and solves for “any” number of bones with in the IK chain Since I did not do our IK I can assume that it was done the same way as I would have done for the need of a 2 bone blend in a 4 bone limb would be to use the limb solve, the ease way, or constraint the the bend and rotation to the parent but allow it to roll freely. One such feature is the look-at where the target would be the next parent in the joint.
The faster solution of course would be to just relink the parent child configuration of the G3 RIG to match Epic’s configuration and you can then make use of 2 bone IK solver with out any messing around but personally this is a feature issue that Epic should “fix” 
I would suggest that you should brush up on character rigging in general as the basics are there
Overall though G3 is just another rig that’s has a degree of complexity that makes it useful in any give situation or need, that is not just limited to video games, but in no way adds obstacles as to unique needs and requirements and there is some clear indications since the release of UE4 that Daz3d is putting some focus into the needs of video game character design.
All in all though it’s just another character design program that really does not solve the “real” problems that needs to be solved but that’s a different subject.