I guess the question is off topic, but since it's here and I was JUST trying to figure this out, I thought I would leave an answer just in case.
You need to find the location of the atom.io executable, atom.exe
. The update is just run to check for updates and then starts the executable with some other commands. I don't think you can use the Update.exe
to start the editor at a specific file, at least not through winscp.
For me, I found that the atom.exe was installed to
C:\Users\mynamehere\AppData\Local\atom\app-0.187.0\atom.exe
So I just copied and pasted this into my winscp editor preferences and it seemed to work fine.
Sidenote: I'm also going to be trying out some of the sftp plugins for atom as they might be better than using winscp if they allow the use of authorization keys. There seem to be plenty of choices.
Update (3/22/16): I found that atom installs itself in the PATH. So now I just add atom as an external editor and use the command
atom !.!