When I got my old Kestrel 4000 back from Kestrel (they repaired a crack and repainted it back in the mid-1990s) there were "pull strings" (fishing line I think) to pull in the cables with. It was a long time ago, but I think I just taped the cable to the string and pulled it through. So, you could attach a pull string to the old cable before pulling out the old cable. Pull the string in and use it to pull the new cable in.

Come to think of it, I'll need to do this soon. The 4000 is now my wife's bike (I went back to steel after cracking it) and I just got her some cross stop levers to add so the rear brake cable needs to come out and go back in. I'm open to any other tricks and ideas this thread may produce.

If Kestrel still existed in nearby Watsonville, CA., I would ask them, but they are gone now. Only the name lives on.