1. search and discover LocalFS
2. decide if it is too old or if it can be satisfactorily patched.
3. patch it (thank you Robert)
4. test, test and test it.
5. Hope that it still works in the next version of zope that comes out.
6. plan to test, test and test it in the next version of zope. And the next, and on and on.
Or you can install plone and know that it has been well tested, it is well maintained and has a large community. One click and you are done. The next version of plone will also be well tested.
Look, you can do it anyway you want but if you want to imply that my suggestion to use Plone is 'insane' you need to come up with a better alternative than LocalFS.
But of course this is all moot. For most installs the best way to use large javascript libraries is to put it into an apache folder.