Metalmayhem;
First of all, I don't know how to do what you are asking.
Having said that...
From my seat in the bleachers, I am not sure overriding homing on e-stop or power-up is a good idea. Assuming you have a Tormach Mill, and unless you have added absolute encoders to the mill, the controller has no way of knowing for certain if the mill is where the software thinks it is - if you hit the e-stop or powered up the machine.
Possibly I misinterpreted why you wish to override rehoming??
Others??
-STrack