If ur having problems overwritng already taken hotkeys try assigning the already taken hotkey to another place on the keyboard first (seems to still work even if if the command is later in the script).
However this is somewhat inconsistent, ie v -'switch colors' works while c - 'color selector' seems stuck.You can disable a hotkey by assigning a null value:
[ISetHotkey,Draw:DrawSize,]
Note that you can only assign hotkeys for interface items that are present when ZBrush launches. So, for example, you won’t be able to change the hotkey for the ZSphere Adaptive Preview.
The hotkey ‘C’ is actually assigned to two interface items and you’d need to disable them both. (I can’t remember offhand the paths, sorry. 
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