(Flash 8) Need help defining alpha values of buttons

programming flash
1

Ok I need some serious help. I need to make the buttons that are associated with this code, toggle, so once you press them they become greyed out. So I was thinking of after you press a button, the alpha is reduced to 40%. Can someone help me place that piece of code into this monster? -I know it should go into the presto function of my script.

Something like… this._alpha =40;

Which works fine, but then it stays at 40%alpha after the user click on a different button.
I need it to toggle off once someone clicks on the next button.

Thanks,
-M


myarray = [];
btnarray = [];
var count = 0;
var p = mc1.mc.createEmptyMovieClip("p", 1);
var q = mc2.mc.createEmptyMovieClip("p", 1);
mc = mc1;
oldmc = mc2;
//you would get this from xml -easy peasy
for (var i = 1; i<8; i++) {
    myarray.push("http://www.pairdesign.net/clients/Don_Satterlee/images/corporate/p"+i+".jpg");
    this["btn"+i].ivar = i-1;
    this["btn"+i].onPress = presto;
    btn1.onPress()
    btnarray.push(this["btn"+i]);
}
function checkload() {
    onEnterFrame = function () {
        if (mc.mc.p._width) {
            mc.swapDepths(oldmc);
            mc.gotoAndPlay(2);
            delete this.onEnterFrame;
            var myvar = mc;
            mc = oldmc;
            oldmc = myvar;
            mc.onEnterFrame = fade
        }
    };
}


function fade(){
    if(this._alpha>0){
        this._alpha -=25
    }else{
        this._alpha = 0
        delete this.onEnterFrame
    }
}
function f() {
    mc._alpha = 100
    mc.mc.p.loadMovie(myarray[count]);
    checkload();
    count++;
    count %= myarray.length;
}
function presto() {
    for (var i = 0; i<btnarray.length; i++) {
        btnarray*.enabled = true;
    }
    this.enabled = false;
    count = this.ivar;
    f();
}