Well, I have not played AP, yet (it will only be available here in Switzerland from 1.4.2010

). But if it is anything like TL then you should simply be able to add it in the hero.txt
Check under your favorite hero type, there should be something like this:
items {
}
Change it like this:
items {
item_name=1
}
Voila, you are good to go...
Item names you can find in the items.txt (again this is from TL and might varie in AP)