I just discovered something kinda neat that might possibly only work for Firefox users. You can get OCN search in Firefox! You can use Firefox's built-in ability for this, but it will give you the black favicon no matter what you do (even though at first it will look like you'll get your preferred favicon). If you'd prefer the classic blue flame favicon (or any custom favicon you're using right now), then you'll need this extension: https://addons.mozilla.org/en-US/firefox/addon/add-to-search-bar
After you get this extension, you right-click inside of OCN's search box right here on OCN's site and choose "Add to Search Bar..." When you do this, you'll get to name it (it's likely that you'll have to) and of course you can give it a keyword which can be as short as one character, as usual. Then you click OK and now you have OCN search built right into Firefox with your preferred favicon.
I have known about adding OCN search using Firefox's built-in ability to add new searches, but I always ended up with the black flame favicon and I wanted the blue one but I could never figure out how to do that. Now that I've figured it out, I'm sharing it with you just in case you'd like to have the same thing.