Here is a driver that will allow you to set the home position via two different ways.  A pop up can come up while outputting giving you a graphic to set the potion number.  And any code can be set to be the default.  Or you can have this turned off and set the value in the CNF file for ATP applications.
The CNF file has a new section called [Home].  There are two settings in home.  One for the home position code and one for whether or not you get the pop up box during output.
The home position will be set using the following line:

position=x
where x can be from 0 to 5

0= G55
1=G56
2=G57
3=G58
4=G59
5=None

The next file will determine if the pop up box shows up.
The pop up box operation will be set wtth the following line:

showDialog=1
If showDialog is set to anything BUT 1, it will not show the dialog and the value of the home will be read from the position value.so if there is no showDialog line or it is showDialog=3, there will be no dialog. Only if there showDialog=1 there will be a dialog.

So in the case that the cnf look like this

[Home]
position=2

There will be no dialog and the value in the Gcode will be G57

if the cnf section looks like this

[Home]
position=2
showDialog=1

The dialog will show up with the default value of G57 and the user can select which home he wants.