As you can see, the lid was printed with a grid of 9 squares. 5 saying 'hit' and 4 saying 'miss'. While this was described repeatedly in White Dwarf as being a 'cunning' design, in reality it is awesomely bad, unless you are a young child who likes dropping small things into a larger thing. The numbers rolled had no effect unless a six was rolled in a hit square, in which case it was a critical.
So what kind of alternative is there? My first thought was to replace it with a d10 system, due to it being the closest to giving nine outcomes. 1-4 would be a miss, 5-9 a hit and 10 a critical hit. Sure, the stats might be somewhat out, but it was close enough. But then I thought that a 60% chance of a hit would be a bit high and I'd rather have 6+ being a hit. As I acquired more of the rules additions in White Dwarf, the result of the d6 roll makes more of a difference when resolving the effects of different weapons, like missiles. I concluded that it made more sense to have one roll to hit and then a second to determine any special effects from either weapon types or receiving criticals.
The result is that I'm opting for a simple 4+ on a d6 to hit, followed by a roll of all successful dice to resolve anything that needs to know what number was rolled in a hit square. This keeps things quite simple and also seems like a Games Workshop-like system with the 4+ to hit on a d6.
The only thing outstanding, is the scatter rule, which again uses the box lid to determine where shots scatter to, meaning it can also 'scatter' into the central square and not just the surrounding 8. The best I can think of for this is to roll a d10 and re roll 0s.
So these are my current thoughts on the subject. When I've had more of a chance to put them into practice I'll update this post if I think they need any amendments.