Well. I've been doing the CWE daily for at least the last 8 years. I'm not sure anymore. I'm Canadian. It's piss easy to get the OTC pills here. I recommend the AC&C pills which come with Aspirin and 8mg of codeine each. I feel that I ought to weigh in my experiences, as they'll no doubt be informative to someone.
In my experience, I've had the best results soaking out the codeine and caffeine (a kind of "schoolboy speedbomb" to myself and my friends back in high school, perfecting the method) by crushing the pills directly into some water with ice in it, mixing well, very well, and then filtering it through an unbleached coffee filter. There's no way really to mask the taste completely. And I definitely recommend waiting until it just begins to hit your brain, and then eating something dense to make it a little easier on your stomach. The solution itself causes heartburn in those who get it.
From a harm-reduction point of view, this method has done me a world of good. I use Heroin semi-regularly, and speedball as a special treat now and then when I can afford it. Because I have the option of regulating my physical habit with codeine, no doctors or prescriptions necessary I can do this and have a job, pay the rent, pay the bills, and survive semi-normally. [from another point of view, a drawback might be that because my life does not become intolerable because of drugs, I'm never forced into a decision making position on the matter] I have had no physical problems from using this method apart from mild heartburn and the side effects of codeine. (constipation, habituation, etc...)
If this method gets too widespread in the countries where AC&C is available, the authorities will catch on, and they will ban the sale of AC&C over the counter. I have kept the method to myself and shared it only with people like myself that I thought it could help. Sometimes, it did. But, I encouraged them to smurf their purchases around lots of different pharmacies to incur less suspicion, and stay out of my area.
That's it in a nutshell.