The first point to make is that the snake isn't "mean" - it's terrified. If you're right about its background, then it's learned (possibly over many years) that humans are dangerous and are going to hurt it. The rattling and striking are just natural responses to a situation where the snake thinks it's trying to avoid the "big pink monster". This behaviour (if such it is) will be very difficult to break through, but your main allies are time, patience and persistant gentle handling. Could take months or years - it might not ever calm down.
Try putting one of your worn but unwashed T-shirts in the tank with him. That will at least get him used to being around your smell (make sure it doesn't have any chemicals on it like deodorant, fabric refresher, cologne or perfume).
I'm a big fan of using gloves with biters. I have one that's never broken out of the habit, although that's because she thinks anything that moves in front of her is food, rather than the behaviour being a warning! The gloves make me less wary of picking her up and they make her much less inclined to strike (the heat and pheramones from my hands are blocked by the gloves, as well as them making a strike less of a shock).