There is a lot one can do with a hacksaw and a file. Even with a zillion power tools, I still drag out the hacksaw every once in a while, and that might be a task that I would have used the hacksaw on anyway.

But...
I think I'd just route the cable, and see how the bike shifts, then modify as necessary.

You could add a piece of cable sheath or PEX, but then where would you anchor the other end? And that might add more friction than just going through the stop, assuming a reasonably straight path.

Glue is good... up until the time you have to disassemble.