Birail problem.... mel command too

i have a problem with a birail that always saying Error: mpBirailSrf1 (Mp Birail Srf Node): birail surface computation failed
so i find a little script on your site to help me
its call railSnap.mel but the problem is what im suppose to do with... its seem very stupid but i look in several post and dont find anything on how to use or install...
i made many try with the scriipt editor but nothing happens.
what im suppose to do... for any of my 2 problem

read the header of the script, and all shall be revealed (essentially, you need to install bonusTools/Games, &/or ensure the closestPointOnCurve plug that comes with it is loading).

railing can fall down even when you have met the intersection condition, presumably due to tolerance? can usually be sorted by budging things around just a tad (or adjusting tolerance?).

ive uploaded a newer revision of the script that makes removal of the snapping constraints easier. sometimes takes a while for the upload to trickle through.

cheers.