In the mean time a Thrustmaster MFD button panel is easy to set up for each salvo you want.  I have button for 1, 2, 4, 6, and 8 salvo settings.  Buy a two pack and split it with someone.  I also have a button to auto calibrate on bomber missions.  I have a button for 3 second calibration and one for 10 seconds.  The Target software is very powerful.
Now another way is to use A voice command system like
http://www.dwvac.com/It works really well.  I press a button that turns VAC on then say "Salvo 4"  and that is it.  Pretty slick.  A squad mate got me going with this and he did the programing.  Great for things like "Return Salute".  One of the best is like fighter hanger downtime.  I say "downtime", "press 2, press 2, press 4" for field 224 then say "fighter"