Ok here is a quick run down of how to do the high idle mod.
First locate the wire harness under the dash, near the OBDII port.
The lower part of the harness with the most wires in it, is the pto harness, You can see in the picture that everything is labeled, you want to find the PTO wire, on my truck its labeled as yellow with a green chaser.
Then i used the #4 upfitter switch to tie into it which in this case the wire is brown. I chose the number 4 switch because it is the lowest amperage of all of the switches (5 amp)
As you can see i just used a butt connector to make the connection, you dont even need to put a jumper wire in, you can just tie the two wires together and your good to go.
To make the high idle work you MUST have the park brake on and the truck has to be in Park. Flip your switch and it should high idle in a couple seconds.
If you do not have upfitter switches in your truck its the switches in your truck, then you will either have to wire a switch up yourself that provides 12v to the pto wire OR you can just hook a hot wire to the pto wire and leave it all the time (not recomended) If you chose to do it this way, any time you are in park with the park brake on it will high idle.
Hope this helps shoot me a pm with any questions.