yes it can be done and no you dont need to be a mechanic to do it....but i can tell you which wire it is someone else will be able to help you....if no-one else chimes in i will try to find out for you
If you pull the cluster out you can tie everything into the right side harness, except the ground. I just ran it to the screw on the fuse box under the dash. In order to find the wire on the right side harness just turn your lights on with the cluster out, ground the gauge by holding the ground wire against the door frame or that metal tube behind the cluster, and then touch the 12v lighting wire of the gauge to the various contacts, one at a time, on the right side harness. When the gauge lights up you have the right one.
For the 12V ign. wire just look on the right side of the cluster. Near the middle you will see "IGN". The "IGN" will be encircled by a gold or copper wire. Follow the wire down to where the harness connects and then match up the gold colored connection with the corresponding wire of the right side harness. You can also just turn your key on and the touch the 12V ignition wire of the Autometer gauge to the open contacts on the right side harness with the gauge still grounded first. When you see the needle of the gauge move up you know you have the right IGN source. This sounds really crude, but it is how I discovered the way to install mine and also some gauges on my friend's Z28. It also allows you to hook up all your wires to one spot, which makes problems more easy to find.
Since the location is easy to find. I tapped into the wire that the ashtray light is on. It is easy to find and access. You just have to run a longer wire from the gauge to IT.
That was the WT gauge on the A-Pillar. Then, when I put in the OP gauge on the Pillar, I tapped into the WT Gauge dimmer wire