dispenser.js

importPackage(Packages.com.sk89q.worldedit.blocks);

var session = context.remember();
var origin = player.getPosition();

var arrows = new BaseItemStack(262, 64);

for (var x = -4; x <= 4; x++) {
    for (var y = -4; y <= 4; y++) {
        for (var z = -4; z <= 4; z++) {
            var pt = origin.add(x, y, z);
            var id = session.getBlockType(pt);
            
            if (id == BlockID.DISPENSER) {
                var block = session.getBlock(pt);
                
                var items = [arrows, arrows, arrows,
                             arrows, arrows, arrows,
                             arrows, arrows, arrows]
                block.setItems(items);
                
                session.setBlock(pt, block);
                
                player.print("Arrows set @ " + pt);
            }
        }
    }
}