Amber Alert won't help find Maddie, it is an immediate first response to abduction. What it does is make sure that the information about the missing child gets to the important people without delay to hopefully contain the abductor to one area and find them quickly. So if a child is abducted the Media, Ports and Airports, CCTV operators and any other source that might be considered helpful are informed straight away, so they look out for the abducted child in Air and Sea ports, CCTV operators are looking for them, and the TV and Radio send out immediate bulletins so the public are aware and can look out for them. In Europe this would also include information to boarder police and even putting up road blocks to check for the missing girl.
Sadly it goes no further than that, if these things don't work within the first 24 hours then Amber Alert is highly unlikely to find the child and in some cases in the US the perpatrators have killed the victim immediately they hear the Amber Alert.
The UK already has a similar system in operation, the police control it and decide what is appropriate I believe, but it does the same thing, although we are lucky that we are an island - it makes things a little less complicated.
The UK has no power to insist that any EU member impliments an Amber Alert type system although we can vote for one if it is raised through the EU.
The McCanns are doing a great job of encouraging it, and it is needed in mainland Europe without doubt, but Amber Alert is a last resort in protecting our children, by the time Amber Alert is used the child has already been snatched. The front line in protecting children against predators should be parental supervision.