To change "mouse position" to a different voice command, open the config/modes/basic.yaml file. In that file you will find the command:
- name: "mouse position"
description: >-
Activates the "mouse pixels" exclusive mode to control the mouse.
biasFactor: 1.2
alternates:
- "mel's position"
functions:
- name: "toggleMode"
fixedArguments:
- "on"
- "mouse pixels"
- name: "openMouseGuide"
fixedArguments:
- "pixels"
Just change "mouse position" to any voice command that you like. For something that you say very often, it is good to go with one or two syllable words that are easily recognized and that you rarely say. For example, "shoe" is short, easy to say, and you probably don't say it very often. If you do need to say it, you can just say "escape shoe".
You should also update the alternates field. These are phrases that will also match the command. Updating this to "shoo" would work well.
You can find all of the information about customizing commands
here.