As already answered, there are many scripts that can be applied to most CMS platforms, but adding the script is just part of the answer most websites need.
There's two consent models in use, implied or explicit.
Implied consent requires you to alert the user to your cookie use and give them options to opt out. There's some free banner scripts that flash up a warning, but read on a little bit...
Explicit requires a more technical answer, needing you to put in a script AND usually wrap all possible cookie serving code (like your GA analytics, your social sharing code, your google maps etc.) in a function so that the script can control the dropping of those cookies. MOST websites will find a big drop off in stats and usage if they go for explicit consent, as most people do not respond with a yes. It's human nature.
Here's the thing:
Whenever you install a plug-in, a videoplayer, google map, analytics, social bookmarking, etc. for the benefit of your client's users experience, you're almost certainly piping in cookies that are not all that you would think. For instance, social sharing plug-ins provide analytics, so most all drop a third party analytics cookie. Popular flash based video players also drop analytics cookies from third parties. The thing is that those 'analytics' cookies often come from groups like quantcast, a behavioural advertising group, so the cookie is tracking and may be considered advertising by the International Chamber of Commerce.
Now, as a designer or site builder, all you've done is put in a plug-in to play some video, or facilitate sharing of content.
There's nothing wrong with using implied consent (in most cases), but all consent must be _informed_ consent. It isn't good enough to put up a take-it-or-leave-it statement in your privacy policy, because that does not allow for informed consent. The guidance is clearly biased to educating web users on online privacy issues and their rights to privacy when using online services. A big chunk of that education effort falls or has been passed, onto the website owner, and consequently on web designers, VAs etc. producing sites for others.
So, to rely on _informed_ implied consent you're obliged to explain your cookie (and similar technology) use, but you shouldn't get too techy about it, as you need to provide it for understanding by the general population.
I'm a business coach and run weekly small business networking sessions, and it was clear that a lot of the advice to owners coming from members VA's and Designers, the people they rely on, was "don't worry, your site doesn't use cookies". We tested that, and guess what, it was incorrect, every time, mainly because of the plug-in and module use.
I'm declaring an interest here as away from the coaching day job I was so frustrated with the problem I joined with colleagues to put together a comprehensive business owners solution, and because we think designers, VAs etc. DO have a role of educator we set it up to share with an affiliate scheme, AND we split out the audit function so you can just get that to run on client sites if you wish as a first stage to building a brief for what to do about their particular site.
In the mid term as public knowledge about privacy online grows we may be in the position where those sites that have don't do anything are viewed with mistrust, and those that whack up a banner without explaining their particular cookie use are viewed with suspicion.
You can see a video at
cookieslaw.co.uk and make up your own mind, but whoever's solution you choose (and we recommend several other people's stuff in our work) I'd urge you to get an audit to find those hidden cookies, because the prospect of installing a browser plugin and visiting every page of a site and clicking on every feature (many, many plug-ins without audits suggest this) is just a horribly time wasting prospect.
And to answer you fully, yes it includes a cut and paste implicit banner solution, which would go into your footer, header, sidebar etc. template or a text widget/module (as long as it takes html) so it appears on every page.
Hope that helps,
Philip Stanley