not sure if this is any good, but it scales on roll over and back on roll out:

just a quick program /script

Code:
attachMovie("circleBtn", "circleBtnOne", this.getNextHighestDepth());
attachMovie("circleBtn", "circleBtnTwo", this.getNextHighestDepth());
attachMovie("circleBtn", "circleBtnThree", this.getNextHighestDepth());

circleBtnOne._x=300;
circleBtnOne._y=200;

circleBtnTwo._x=300;
circleBtnTwo._y=300;

circleBtnThree._x=300;
circleBtnThree._y=400;

circleBtnOne.onRollOver = function(){
	trace("Rolled over button One");
	circleBtnThree._xscale=140;
	circleBtnThree._yscale=140;
	circleBtnTwo._xscale=140;
	circleBtnTwo._yscale=140;
}
circleBtnOne.onRollOut = function(){
	trace("Rolled over button One");
	circleBtnThree._xscale=100;
	circleBtnThree._yscale=100;
	circleBtnTwo._xscale=100;
	circleBtnTwo._yscale=100;
}

circleBtnTwo.onRollOver = function(){
	trace("Rolled over button One");
	circleBtnOne._xscale=140;
	circleBtnOne._yscale=140;
	circleBtnThree._xscale=140;
	circleBtnThree._yscale=140;
}
circleBtnTwo.onRollOut = function(){
	circleBtnOne._xscale=100;
	circleBtnOne._yscale=100;
	circleBtnThree._xscale=100;
	circleBtnThree._yscale=100;
}
circleBtnThree.onRollOver = function(){
	trace("Rolled over button One");
	circleBtnOne._xscale=140;
	circleBtnOne._yscale=140;
	circleBtnTwo._xscale=140;
	circleBtnTwo._yscale=140;
}
circleBtnThree.onRollOut = function(){
	trace("Rolled over button One");
	circleBtnOne._xscale=100;
	circleBtnOne._yscale=100;
	circleBtnTwo._xscale=100;
	circleBtnTwo._yscale=100;
}
simply add the alpha code in each button, circleBtnOne._alpha=50; on over the =100 on roll out

si