From my experience, doing that on a website is not *very* hard, but I'm afraid it's hard enough that people may start, bump on a few obstacles and then give up (because there's a whole lot of other features they have to implement on their website).
On LibreJS home page , it says
As far as my (little) experience with it goes, the browser extension is fine. In my opinion it's far more useful to focus efforts into making LibreJS a breeze for web developers, otherwise only very few websites will bother to comply with its standards.
I'd like to give you a few suggestions about how you can do that. The suggestions below are in decrescent order of usefulness.
I strongly believe that implementing those changes will have a considerable impact on LibreJS adoption
1) Live demo examples
This webpage  seems to be intended to be the primary source of information for web developers who want their websites to comply with LibreJS.
The topics under [Step 3: Adding license information] desperately needs live demo examples, that shows what works and what doesn't, and explain why.
I was both pleased and annoyed when I found out that there were live demo examples available, but they were "hidden" in the Appendix C of the documentation . Also it's probably a good idea to have a big link on  pointing to .
2) Weblabels first
Web labels is probably the easiest/fastest way to do it, and yet  only kind of mentions it as "last resort" method, "if bandwidth is an issue".
I think describing how to do weblabels should be the first topic under [Step 3: Adding license information]
3) Document the hidden obstacles
When updating freedomsonsors I bumped into a some unanticipated, nontrivial (pun intented :-)) roadblocks. I documented them here . I think this info should be available on the official documentation. Or better yet, document this as Questions+Answers on StackOverflow and have  point to them.
Isn't it a shame that searching for "LibreJS" on StackOverflow return 0 results?
4) Build a online testing tool
It would be awesome to have an online tool that could test any given website against LibreJS standards.
Paste your URL, get the results. Is it possible to build such a thing using NodeJS?
5) Have a proper issue tracker, and encourage people to use it.
This is 2014, no Open Source project should be talking about bugs via email.
And don't get me started on Savannah :-)
That thing is so ugly that it's a pain to look at. I think it *hurts* LibreJS to leave its issues there.
People probably will unconsciously avoid touching those issues because it looks so ugly.
Also, I think it's not a good idea to separate bugs  from tasks .
A much better place for it would be gitorious . It's issue tracker is much more beautiful, and it also makes sense to let the issues live close to the code.
Actually, I think you should even consider to (7)
6) Have a list of cool compliant websites
It's probably a good idea to have  point to some cool compliant websites, like rootstrikers.org
(I only found out about this by change, on the mail list), and freedomsponsors.org
(hehe ;) ).
7) Let Gitorious be the single source of information about LibreJS.
It has a wiki, and an issue tracker, and a git repo. That's almost everything an Open Source project needs in terms of tooling.
Let GNU's website be about GNU, and have it point to LibreJS's resources on LibreJS project pages.
This is it. I hope you find it useful!
Tony Lâmpada - the guy from FreedomSponsors