anti-theft scanner

Okay What kind of scanner do you have? Most scanners have a 3 wire set up.

1. Black for ground (-)            // This goes to the chassis or bare metal  

2. Red or Yellow for Constant Power (+)     // This goes to the battery (+)or an accessory fuse that always has power what ever is easier for you.

3. Usually Blue ( For activation when armed)  // This goes to an accesory  fuse that only has power when the key is on. Or if your scanner has an on and off switch you can delete this step.

Since you do not have an alarm from what I undestand of your question. You can just wire the ground and possitive wires and that should takecare of you.  Good luck