bose, I hope this picture helps to illustrate:
This is my L2 with an unknown drop-in gifted to me by mitro. The 40 guage copper strip is 18-20mm wide, cut from a roll I got from Hobby Lobby. As you can see from the photo, this width covers from just over the reflector curve down to slightly over the spring. The actual flat spot on the drop-in is about 16mm. Doesn't really matter because the actual contact area (the dark strip in the center on the drop-in) with the host is about 12mm. After much trial and error, I settled on the 18-20mm width as narrower widths tend to slip when pushing the drop-in into the host. I used the Ceramique as a kind of glue to hold everything in place. It's very thick and sticky, so only a small dab is required, plus it is after all thermal paste, so it should help or at least not hurt heat conduction of the copper.
Start with a few small dabs to hold the strip in place on the drop-in, then start tightly wrapping it around. I put another dab of ceramique in there about every two wraps. With 40 guage, 6-7 full wraps will be adequate, but the exact cut out is different for every light and takes some trial an error to get right. After finish the wrapping, I'll continue to twist it in the direction of the wrap until it is completely flat and very tight. Then peal back the last 1" or so, spread a thin layer of ceramique on it to hold it in place. Then twist again until it stays flat and in place. Be careful not to get the paste near the edges, as it will spread out and get everywhere.
When you push it down into the host it should be a verrry tight fit to assure contact and thermal conduction. Use a screwing motion, going in the direction of the wrap so it stays tight and in place. The wrapping above is nice and snug. The wrapping on my L2P is so perfect it takes all my strength to remove it from the host.
Hope this helps. Expect to have to wrap/re-wrap and cut the strip until you get the best fit.