I have to say, those are some pretty strange instructions. You don't need to have a track pointing to the MIDI device to set up the MIDI metronome. But you
do need a decent quality hardware synth to generate the sound with an audio track to echo it's output through SONAR if it's not direct-monitored. Your wavetable synth is probably not going to cut it because the latency is going to be too high. And I don't think you can use a soft synth without jumping through some hoops.
I recommend you just set up a MIDI track with notes on quarter note beats to drive a drum synth's side/cross stick. A MIDI groove clip will make it easy to drag out to the length of the project.