You shouldn't need any external programs. When you check the "Launch with Windows Start" option, VoiceAttack should immediately be added to the list of startup programs.
This can be verified by opening task manager (Ctrl-Shift-Escape opens it directly in most cases), and checking that "VoiceAttack" is listed in the "Startup" tab.
If you're running VoiceAttack as administrator using a different user account, that may prevent this from working.
In that case, temporarily disable the "Run VoiceAttack as an Administrator" option, restart VoiceAttack (you should see "VoiceAttack privileges not elevated. Pro Tip - If you are having trouble with key presses being recognized, try running as an administrator." in the log), check the "Launch with Windows Start" option, then check "Run VoiceAttack as an Administrator" again.