Executing Commands From Windows Service

[T]

I have a script, which runs as a Windows service under the LocalSystem
account, that I wish to have execute some commands.  Specifically, the
program will call plink.exe to create a reverse SSH tunnel.  Right now
I'm using subprocess.Popen to do so.  When I run it interactively via
an admin account, all is well.  However, when I'm running it via
service, no luck.  I'm assuming this is to do with the fact that it's
trying to run under the LocalSystem account, which is failing.  What
would be the best way around this?  Thanks!