I believe you can disable any keyboard using the technique I used in this thread. The link below shows how to disable BOTH HTC KeyBoards (one called HTC KeyBoard and one called HTC KeyPad). Look at the parent GUID key for the name and Search for other IsSipInputMethods through the registry and choose which you want to disable.
http://pdaphonehome.com/forums/htc-t...-keyboard.html
However if "One KeyBoard" functions in two ways depending on context and you want one context but not the other then you're out of luck. But I believe each keyboard is registered seperately. But I may be wrong.
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EVO 4G, Stock Sprint ROM, ProClip in Car, Sony HBH-300.