Note: Writing this in the Community Docs section until I get it cleaned up enough to put into the Official Documentation
Simply use the svn+ssh URL for access. eg., svn+ssh://firstname.lastname@example.org/p/fancypants/svn/
TortoiseSVN doesn't need any extra configuration to use svn+ssh, however as it doesn't save your password, it will continue to prompt for the user password whenever needed, which may be multiple times for a single checkout or commmit. To get around this, we recommend using pageant with an SSH key
USERNAME@svn.code.sf.netas the key comment. Make sure to save the private key data.
So you don't have to repeat step 4 every time you start your computer, you may want to configure pageant to startup automatically with Windows
This guide may also be useful.