Question: I have an old website, and I would like to add a glyphicons to a page of this site.

I cannot install bootstrap (link bootstrap.js and bootstrap.css to this page) because it will change all styled elements on the page.

Is there a way to add only "glyphicons functionality"?

Answer: 
I prefer to use something called 'font-awsome' it has a huge library of icons and it only takes one line of code to include it into any project. - It works the same way as glyphicon being able to format with CSS etc.

I know this is not a answer to your question, but its a valid work around, and I prefer the font-awesome icons.

<http://fortawesome.github.io/Font-Awesome/>

View here how to include it on your website:
<http://fortawesome.github.io/Font-Awesome/get-started/>

Have Fun!
You can download glyphicons png on <http://glyphicons.com/>