I want to create additional icons that look like the Measure tool icons.

[WorkPlayce]

I want to create additional icons that look like the Measure tool icons and have the same behaviors for hover and pressed.

Can you provide the syntax (whether javascript or css) to which I can just provide the path to my own icon images and hook events?

[JonathanUihlein]

In esri.css :

.esriMeasurement .distanceIcon {
    background-image: url("../dijit/images/Measure_Distance16.png");
    height: 16px;
    width: 16px;
}
.esriMeasurement .areaIcon {
    background-image: url("../dijit/images/Measure_Area16.png");
    height: 16px;
    width: 16px;
}
.esriMeasurement .locationIcon {
    background-image: url("../dijit/images/Measure_Point16.png");
    height: 16px;
    width: 16px;
}

You would need to override the above styles with your own.

The buttons are standard dojo ToggleButtons.

dijit/form/ToggleButton — The Dojo Toolkit - Reference Guide