If i understand your question you want to bind a specific phrase from the voice menu to a certain key using the command console. You can do that in this way:
Need Dispenser =
bind <key> "voicemenu 1 4"
bind <key> "voicemenu 0 1"
But you can't single out a single type of response from the selection.
e.g. You can't choose between
Thank you! when using the command mentioned above.
It may be possible to do this with a script though but from what i know it would still generate some kind of a random response.
Left 4 Dead it was possible to select a certain response from the list.
EDIT: You can't bind the voice responses triggered by events to a key, only those from the voice menu.