Super easy to do you have 2 stock horns so find the positive wire and trace it back to before it splits into 2. Cut that wire and run it back into the cab to wherever you have the switch. Run one back to the other side of where you cut it. Now what I did here is I put separate switches so I could turn on whatever I wanted individually or all at once, but you can have a 3 position switch too. I could probably do up a wiring diagram if you wanted.
I have a switch so I can toggle between stock horn and train horn for my steering wheel.
I used to have a button on my floor, but I kept accidentally hitting it and scaring myself shitless so I moved it.
Im going to try it tomorrow, I already have a 3 position toggle switch I can use.
Ill let yall know how it works out tomarrow.
Ok good luck 
Good luck buddy!
I have it wired through my factory horn relay with a toggle switch hidden under the dash to switch between stock horn and the best.
That will help, I didnt have a chance to do switch yet but Im still going to it.
I used the stock horn location, and like many can toggle it with the stock one.