Source: Taping Tyco TrackTaping Tyco track
I found 5mm wide, adhesive backed, copper tape at www.hobbytronics.co.uk.
I stripped out the steel rails by gripping and pulling them up with a pair of side cutters.
I cleaned out the rail slots so that there was nothing to catch on the tape when inserted.
I cut a generous length of tape, stripped the backing cover, and holding the copper in gentle tension between thumb and middle finger, fed the tape into the slot with the index finger. It's tricky but you get the knack of it eventually.
It only goes in 2mm so I was able to fold the protruding excess over towards the guide pin slot. I flattened the surface with a hard smooth tool (a stainless table knife handle) to get the adhesive down and any wrinkles out. Curves are trickier but not impossible and need more flattening and stretching to get the smooth surface needed.
The excess tape length is used to wrap a connection between track pieces as they are joined up. It's also tricky as you're working underneath the track as you lay it down.
The end result was worth it though.