Do you have any paticular lessons that were super effective at breaking them out of their "I hate English" shells? An activity or game that really got them involved?
I found quite a few techniques that students enjoyed that also helped them to learn English. You can read my collection of Teach ESL articles at this page: Teach English. Those are, basically, the best of what I have to offer. There's not much more than that, but I found those to be very useful in many, or even most, situation.