Adding Font Awesome 4.3. icons in Theme Configurator

[Romerito]

I'm trying to add the whatsapp font awesome icon -  http://fortawesome.github.io/Font-Awesome/icon/whatsapp/  - within one of the hooks of the theme configurator. 

 

So I want to change the following code:

 

<span class="ca-icon"><em id="icon-envelope" class="icon-envelope"></em>
</span>

for something like 

<span class="ca-icon"><em id="fa-whatsapp" class="fa-whatsapp"></em>
</span>

 

How could I achieve this?

 

Thank you