to bind a voice command you have to put it in this format
bind f "voicemenu 0 5"
f = the key you want it bound to
the first number is which voice menu you want Z=0 X=1 C=2
the second number is which thing you want to say except -1
ex. if you want to bind 'cheer' I believe it is C3 (2 takes the place of C and 3 is the position of Cheer in the menu, dont forget to subtract 1 = 2)
that would translate to bind f "voicemenu 2 2"
make note that in the console you need the " " as well
hope that helps