The EU cookie law has been discussed before on this thread, as well as here and here. As far as I understand it does not apply to authentication cookies or cookies required for functionality to work correctly. The main concern would be for tracking cookies such as for google analytics (or cookies for ad tracking affiliates sales and such) and if you have to prompt for that you might as well just stop using analytics or those other cookie dependent things because you will only track the small percent of people who would actually click yes to such a prompt.
It is such a stupid law that I do not think it merits development effort to comply with it. I would never put such a prompt on my own site or recommend a customer to do that.
Think about it, most web sites primary purpose is marketing and call to action and what does this prompt do other than become the primary call to action distracting from all other calls to action that your site is really trying to promote and communicate. It is a poison pill.
Since it is not required for cookies that must work in order to use the site and only applies to other things like google analytics or ad tracking cookies my advice is if you must comply with the law then do away with that kind of tracking rather than add this onerous prompt. For example if you interpret that law to mean you cannot track users in google analytics except for the small percent of people who opt in to the prompt then google analytics will be basically useless so you might as well ditch it and just use IIS log analysis tools like SmarterStats instead of putting in this really bad prompt that distracts from the main purpose of your site. Its just ridiculous to do that in my opinion especially since hardly anyone is ever going to click yes and the vast majority of people will be put off by the prompt and maybe even leave your site as a result of it.
The law makers who wrote this stupid law just need to be prompted by having their arses kicked in my opinion.