Turbo can't be blocked. On WAW its easy to get by.
Instead of your controller reading RT,RT,RT,RT,RT,RT,RT...quickly. You set the wires up so it reads... RT,RT,RT,dPAD down, RT,RT,RT...very quickly instead. Because everytime you push down on the d pad it resets the timer/counter.
It's not as good as the old turbo pads, and it there is a slight pause every three shots. But because it's being read so quickly it's pretty much fully automatic.
The other problem with this, is that it is simply too much work to make a controller that reads like that. I made one for myself, but to mass produce it's a pain in the ass.
Also, it only works for COD, as other games have a function for D-pad down. While COD doesn't have any function for dpad down, at least online.