Spindle Setup Encoder on motor gear change

im having problems figuring out how to write the hal for my spindle set up. my encoder is mounted to the motor. i have a 2 speed spindle so i need two scales for the rpm and i need a button in axis so i can tell emc which scale to use preferably a button or check box to select between hi and low gears. right now im usindg a pid loop and i dont need to, nor want to. also i only have it setup for one scale, hi gear. i have looked in the git sample configs and cant find anything close enough to my set up, everything i have found the encoder is mounted to the spindle and they are scaling the pmw not the encoder. thanx in advance.

thanx andy that helps. how does one add a couple check boxes to axis, preferably under the spindle section for high or low gear. cause as of right now the machine has no way of knowing which gear it is in.