Ok so what you need to make this work is: (note this is for windows 7)
A Mic
Windows Speech Recognition (found in~: Start menu/All Programs/accesories/ease of accesss/windows speech recognition)
and the GlovePie Software found here:
http://glovepie.org/lpghjkwer.php
You do not have to modify MnB at all, basically it works like this.
Windows speech recognition is how your computer identifies the vocal commands, basically if you say the word 'archers' WSR(Windows Speech Recogntion) recognises your voice and converts that sound into the text 'archers'. GlovePIE is the 'bridge' between WSR and your keyboard. when WSR hears 'archers' GlovePIE takes that and turns it into 'press 2' on the keyboard.
By adding the code from the above link into glovePIE and saving that code and running it (A big run button is in GlovePIE) in the background along with WSR while you play warband, this will allow you to do various things via voice command
(I will try and add a link to my GlovePIE Code file that you can just add to the GlovePIE save folder when I have it working.)
I am currently having a little trouble with using WSR to recognise the words, I am about to experiment with training WSR and adding in my own recorded voice commands into WSR's recognition.
I have so far been able to select 'archers' as a group and also add my own custom command 'up' which nudges the screen up on the world map, but the one pair of custom commands I really want to see if I can add and make work is 'EYAR' and 'WOAH' to make my Horsey speed up and slow down using my voice
muahahaha.
Voice commands could be really fun when the next SoDW version is released with the new voices element. Think of it, you tell your archers to 'Hold' and then your right hand man yells 'STEADY LADS, WAIT FOR THEM TO COME!' or some other equally colloquial phrase
EDIT:
Well I discovered the problem with WSR I had to add an input boost of 10db on my mic so that WSR could hear me properly, before that I was having to swallow my mic in order to be heard. It seems to be working like a dream
I have successfully ordered my archers to follow me and I can make my horse gallop by shouting 'eyah' in a typically horse riding hero fashion!