I recently switched to Colazal.
The directions for 12 weeks that you've mentioned may be due to a a disclosure by the manufacturer that "the safety and effectivess of colazal beyond 12 weeks in adults have not been established (beyond 8 weeks in children)".
Rio, 31 yr old male - diagnosed with UC in 07/2006.
Alternative therapies for several months (SCD, ayurvedic treatment, VSL#3): didn't work and became anaemic. Canasa, 2 daily: remission for a month then flared-up.
4800mg Asacol (6 x 400mg, twice a day) & Aloe Elite.
Completed first (6 week) tapered course of Pred in 10/07, flaring up since coming off it.
Currently on: 12 x 750mg Colazal, Cortifoam once a day, Nature's Way Probiotic twice a day.
Diet: Cut out caffeine and alcohol after diagnosis. Been vegetarian for many years. Low dairy, low carb, and avoiding foods that are processed, fried, spicy, acid forming, fungal, contain yeast (i.e. I don't have a life, but desperate times call for desperate measures!).