I solved this problem on my 98 rolla VE just last week after literally months of living with it. I noticed one day as I was driving that when I pulled the seat belt out further away from my chest toward the steering wheel the blinking stopped. It would start blinking again when the belt was back against my chest. With further experimentation I found a sweet spot where I could make it blink, or stay off.
What I did to fix it, is when I exited the car, I would carefully make sure that the seat belt strap was completely retracted into the pillar. The next time I got in the car and put the belt on there was no more blinking. Since then I have been more careful about making sure the seat belt is fully retracted when I exit and I haven't seen the blinking light at all for about a week.