Running command executable build from another user

Hello

Some days ago we move all our source control projects to svn+ssh access policy. With that we lost any checkout functional from our runner.
Though we can checkout source from simple command line in server terminal. It is because our tunnel has written for Adminitsrator user.
Actually TeamCity works under SYSTEM user and possibility to change subversion tunnel is not accessiible for that. I have tried to use runas
command with passing password as

runas /user:Administrator svn ... < my_password

but no result.

My question: Is that possible ways to execute our runner? Because it is some uncomfortable to use TeamCity, and make it works with svn+ssh
in runner.

You can ask me to give more explanation because I am not good in english

Thank you.