The function is now included in the Blender Addon (
Reference Post)
Video-Demo of how the function is used is uploaded here:
You basically select the function while the (static) item is selected, choose your target size (the largest dimension is scaled to this size) and the method (default should usually be the best choice). All methods except "CubeMesh" should be non-destructive, meaning you can revert them anytime by just removing/disabling the armature modifier.
I will stress though that the game still thinks the object got its original size. Consider this when generating your LODs, hitchecks etc. (large objects can be especially frustrating to select, as you will have to find the original hitbox).
Again, Wagi's linked post is your best option when dealing with animated objects. The addon's ScaleHack can only be used as static objects, as it introduces its own armature and keyframe.
Here is a proof of concept item you can subscribe to on the workshop:
Moai 100m (low poly)