Yes, it's pretty simple.
You would first have to download the ARM version from
https://syncthing.net/downloads/
Then you run syncthing.
You can then either adjust the config to temporarily allow outside connections (by default on port 8384), but easier is to do it through an SSH tunnel. With the SSH server in KOReader:
Code:
ssh -L 9191:localhost:8384 root@192.168.1.213 -p 2222
(192.168.1.213 is the IP of my H2O)
Then you can configure Syncthing on
http://localhost:9191/ (or whichever port you put in the tunnel).
You could write a simple shellscript to start and stop Syncthing from the KOReader file browser if desired.