What if you want to do this with the control rotation and not the actor? I need the entire character to rotate including the way in which it handles. I tried doing this
FTransform orgRot(FRotationMatrix::MakeFromZX(GetCapsuleComponent()->GetComponentLocation(), GetCapsuleComponent()->GetForwardVector()).ToQuat());
FQuat addInRot = FRotator(0, mouseX, 0).Quaternion();
orgRot.ConcatenateRotation(addInRot);
Controller->SetControlRotation(orgRot.Rotator());
and it results in the character turning over on its head as I approach the poles of the world.