You have to practice putting different pressure on the two strings, with two fingers...
I think you can listen to the great Jerry DONAHUE, he is totally awesome...
I think there are some tricks too, where you can try and copy those bends.. I think you should start by copying B-bender style bends (one note goes up, the other stays in tune) they are far more effective than two notes bends... There's a trick that goes 'you wannabe a hellecaster' that I have posted, and you can try to play it...