Neil,

Glad the post was helpful.

What you're talking about is certainly feasible, but be forewarned: soldering to the copper on the flexible foil requires a bit of patience and is unforgiving of mistakes. The nylon (?) which houses the circuit melts very very easily.

When I actually soldered the wires, I used a couple pairs of surgical forceps to hold the wire in place. 

Double check your wire-ups before you solder, as you'll probably not get a second chance to make it right. 

Also make sure any connections between new wires and the existing foil are mechanically sound. Soldering takes care of the electrical connections, but you want to make something more secure in a car that's going to be bouncing around on the road. Your proposal to punch a hole in the foil circuit might do the trick, depending on the sturdiness of the foil where you make the hole. I would use a drill with a very fine bit. You might think of using a glue gun to secure the wire after the soldering is complete. 

Definitely use your spare for practice and testing. That's how I figured out what could be done in my own case.

Good luck.

-Jarrett

On Mar 26, 2013, at 12:06 PM, neil n wrote:

> tips on soldering wires to the traces would
> be most welcome.
> 
> Also, it occured to me that I could carefully punch a hole in each
> trace, bend each wire, then insert to help align and secure wires
> before soldering. If that's a bad idea, please advise. I do have a
> spare slightly damaged (maybe fixable) ribbon I could practice on.