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gameplayercontrol is a global so you can simple overwrite it with your own version, i.e.:
gameplayercontrol = require "scriptbank\\yourgameplayercontrol"
As long as you do this in one of your in-game scripts it should replace the default.
I would do this with a bit of logic to ensure that regardless of timing your version will always persist, i.e. in an always active script:
local mygpc = require "scriptbank\\mygameplayercontrol"
... in _main function:
if mygpc ~= gameplayercontrol then gameplayercontrol = mygpc end
Make sure this is only present in *one* script though!
Been there, done that, got all the T-Shirts!