I think you are right about how slippery elm works, that is why the pills and extract are probably not going to be as efficient, however easier to consume.
As far as activated charcoal, there is another 'treatment' called a P&B shake that is supposed to work like charcoal.
It is psyllium (fiber) and bentonite (clay). You mix these two together and drink the shake. The psyllium (plus it's seed) kind of scour the bowel, and the bentonite (volcanic ash) sucks up loosened toxins.
The trick is to find both ground psyllium and seed. And the bentonite should be hydrated. If you can't find the psyllium seed, you can throw in flax seed (1/2 tsp).
This isn't hard on your system, but you probably just want to do is 2 or 3 times a week over a month (at night?). Check for progress, and repeat if you think it is helping, but haven't reached your goal.
Here is a link on P&B, but there are many others.
http://healthychristianliving.com/clean_out_the_gut.htmI am still under the impression that you should then use acidophilus to replace healthy intestinal flora. (Not at the same time.) It is much stronger than yogurt. I spoke with a health food store owner yesterday who said that you should take oregano oil (kills candida and other parasites) during the day, and acidophilus at night, because most of your healing is done at night.
But sometimes, I think our bodies need to take a few days off from detoxing. For me, that doesn't mean going off my diet, tho. I had about 80% coverage 2 months ago. I'm seeing real progress, but I will need to persist with this for awhile.