You can get flax seed fiber supplements (intestinal cleansers is what they're usually called) same as you can get psyllium, and can take the same amount. :)
You can also eat whole grain breakfast cereals that have flax in them, it's a great grain, really healthy oil.
Eating fresh apples and taking intestinal cleansers with flax and apple pectin is also a good way to go. I don't eat much fruit, but I do try to eat a green apple several times a week, they're so good for the body, and the Fujis we get from the farmers market taste great. :)