This screenshot is part of my shelf I use when modeling, from left to right: Delete History, Center Pivot, Freeze Transformation, Instance X-1, Instance Y-1 & Instance Z-1
You can download the icons by "Save Image As.."
Although "FreezeTransform" has a direct icon in Maya, I customize it to better differentiate of "CenterPivot"
Below, Instance Icons and MEL code for each one
instance; scale -r -1 1 1;
instance; scale -r 1 -1 1;
instance; scale -r 1 1 -1;