You can try retargeting, but that might be a pain, and even if it does work, you’ll most probably still end up with some bones deformed, so you’ll have to either tweak the animation manually or tweak settings on the skeleton (Recursively set all bones…).
Another way is to simply unskin the DAZ character and reskin it with the SK Mannequin rig (Epic’s Rig). If you do that right, the anims should work without problems.
Another way is to take the SK Mannequin Rig out of UE and into a rigging engine like Blender/MAX/Maya and add/remove bones to/from it to make it similar to the DAZ Rig, while still keeping the animation. Note if you get this right, when you import back into UE, it’ll be a new skeleton, and the animation may not work on the standard Epic Rig.
Basically, there’s no easy way to do it, yet, as far as I can tell. If anyone has an efficient, easy way to do this I’d really love to know, cos I actually need it as well.