You do not even have to waste your time placing code in the head section of your homepage to get a favicon to appear on every page of your site. It is usually sufficient enough to place your favicon image in the root directory of your server, and browsers will (eventually) pick-up that you have one for the site. It doesn't take long though.
Although your icon file needs to be named favicon.ico, so browsers will recognize it as a favicon.
In case that it does not work as described by jrg_newtojs (as it's server and CMS dependent), you can place the code in a recurring element of your website - in case your website is dynamic. Our system, for example, offers automated META tag placement for every page - try to see if your CMS offers the same.