Varad Scanner Hook Up?

[Savage420]

Hey, i bought a Varad Raptor LED scanner. Im trying to hook it up and put it behind my rear view mirror, BUT there is three wires, one is red(power), one black(ground) and one orange (ignition).

 

Sooo what i cant figure out is where i can hook the ignition wire into...would i splice into some wire under the dash or under the hood in the fuse box????What would be my best bet?

 

Also should i run the power and ground right up to one of my battery's, or some place else.

 

Picks of where the i should put the wires would be great!!!

 

This is in my 02 Sierra2500HD