[AS3] checkbox component

[untitled88]

I was wondering how to disable and enable a button within the following if statement:

if (a_mc.box.selected&&b_mc.box.selected&&d_mc.box.selected) {
trace("Disable remaining CheckBoxes");
}

I'm basically trying to figured how to get various properties such as: selected_disabled within a checkbox button through AS3?
Any help would be appreciated.