AFAIK alpha to coverage is enabled by default on any alpha masked materials when using the forward renderer and 4x MSAA since 4.15. The only extra “trick” needed is the fwidth() sharpening of the alpha map. Unreal doesn’t appear to have an fwidth() node, but it can be reproduced with the ddx and ddy nodes.

fwidth(x) == abs(ddx(x)) + abs(ddy(x))