Hittest diagonal

Hello guys,

I’m busy now with a game now. I’m having problems with the hittest. I found a nice tutorial on flashfocus.nl. Maybe the dutch people know the site…But anyway, I had to move my charachter on a perspective way as you can see i the code or fla:
var heroW = 10;
var heroH = 20;
//var velY = 0;
//var stepS = 8;
var stepX = 8;
var stepY = 4;
//var jumping = true;
var grondY = 380;
this.onEnterFrame = function() {
if (Key.isDown(Key.UP)) {
for (var i = 0; i<stepX; i++) {
hero._x–;
}
for (var j = 0; j<stepY; j++) {
hero._y–;
}
}
if (Key.isDown(Key.DOWN)) {
for (var i = 0; i<stepX; i++) {
hero._x++;
}
for (var j = 0; j<stepY; j++) {
hero._y++;
}
}
if (Key.isDown(Key.LEFT)) {
for (var i = 0; i<stepX; i++) {
hero._x–;
}
for (var j = 0; j<stepY; j++) {
hero._y++;
}
}
if (Key.isDown(Key.RIGHT)) {
for (var i = 0; i<stepX; i++) {
hero._x++;
}
for (var j = 0; j<stepY; j++) {
hero._y–;
}
}
};

And then i saw the hittest code for regular movements see below for the left:
if (Key.isDown(Key.LEFT)) {
for (var i = 0; i<stepX; i++) {
hero._x–;
for (var j = 0; j<=heroH; j++) {
if (ground.hitTest(hero._x-heroW, hero._y-j, true)) {
i = stepX;
j = heroH+1;
hero._x++;
}
}
}
}

But for somehow i cant fix the hittest in my code. Can someone help me?