I just had to get the exact same freewheel off a 30 yr old bike. It was on there GOOD. I used Tip #1 from the first reply post... I really had to crank on it, and when it did finally come loose it felt like something was breaking (but nothing did... it was just really on there.) Make sure the vice is really secured first (I ripped mine right off the bench the first time).

Make sure you axel nut is not tight, its only used to keep the remover tool from slipping. So it should be against the remover tool, but there should still be play in the remover tool. And like it says above, once it does start to turn, take the axel bolt off.

I also let some chain oil soak into it.