if you want to test irregular shapes against points, you'll want to look into hitTestPoint. so for your question, here's an example of doing just that.
ActionScript Code:
//hitTestPoint(x, y, shapeflag)
if (mc.hitTestPoint(mouseX, mouseY, true)) {
trace("hit!")
}
another thing is that getBounds is used differently in as3. since the getBounds method returns an instance Rectangle, you would first create that rectangle with a variable so you can reference it later. once you have done that, you have access to it's properties:left, right, top, and bottom, which are the equivalents of xMin, xMax,...etc.
ActionScript Code:
var boundaries:Rectangle = mc.getBounds(this)