Well, there is an easier way (although it looks more complicated from the ammount of text)
A speech order always has got three digits, i.e it looks like this :
speech 4 14 0
All these numbers can be dertermined by simple counting (more or less)
Just go to the 'Vote'menu (the ingame menue, where you can vote restart, another loadout...)
There is a section Speech, here you get your first digit
(IMPORTANT: the first item is always 0, not 1)
So a 0 leads to Acknowlegde, a one to Check your fire...
The only problem here is: 2 are the orders, used for commanding i.e.bots. So the taunts are 3 and the other/misc section is 4 ...
Second digit:
Just count again, we want a speech from the other misc section, let's say :Contact.
We get a 7.
Third digit: Just for sending a message to a certain soldier. I think used for orders only. Again can be counted, so a 0 to All...
When you want now to bind a key with the console, always fill up unused digits with 0, so for this contact example:
set input <key> speech 4 7 0.
This should be easier cause you do not have to use this voice bind menue and leave the game afterwards to get the numbers.