I've got mine wired in-line with the stock horn and recommend this setup. This way, you can tap the button to give a friendly "beep" to say "hey"...or you can hold the button down to really get somebody's attention.
I bought my bike with the horn already on it. The only downer is that the PO mounted it on the kickstand crossmember brace. I had to take it off for the permanently mounted lift adapter. I'd recommend finding a different spot to mount yours so that you do not have the same issue.
I had mine mounted to the "permanently mounted lift adapter".