You can "stress" your plants a little. Stop watering them as much (if you water them). Stressed plants want to get their seeds distributed and will ripen quicker.
I wouldn't over do it, but a week without rain or manual watering, when it's cool, will generally trigger ripening here. It's worked well for me with tomatoes, but I've not tried it with peppers. I really like red peppers, but they are slow.
I've grown earlier varieties, but when it's cool, they just stay green forever!