I have just purchased a 3 bangs for your butt, I am wondering how others are getting on.
So far I haven't even managed the first bang, maybe I'm just a pussy!!
Any tips? Or is it just lube and perservance?
With any toy that sort of size, it's always going to be about preperation, patience and yes LOTS AND LOTS of lube.
Ideally, you would have been working your way up from smaller size plugs - allowing your sphincter to get used to be stretched. If this is your first anal toy, it might take a while to get it all in - but not impossible.
Just relax, take it slowly, lube, lube and more lube - and if it hurts - STOP.
Good Luck! 
You have a 3 bangs Dave?
Sadly, not - i'm not that far advanced with anal play - the biggest circumference i've been able to take so far is 6 inches ... however to even get that far, it took a lot of patience and practice. I would never dream on taking on something like that without A LOT more practice.
However my routine is to start with a small plug, and gradually move on to bigger plugs, until my body is ready to take something bigger - if you've never taken anything that big before, you will struggle - like any muscle in your body - your sphincter needs to be warmed up!
It depends on what you've used before, it's not a starter toy(even the 'medium' size), you need to be able to handle something slightly smaller than the top is, easily, then just take TIME and work up gradually.
The length can be a problem as it can be a bit bendy, use some smaller plugs to work up that have a nice long taper to make it easier, one day you may get up to me, mines "rather large" it's 3.5"x4.25" oval diameter, the largest that will fit through my pelvis.