You can add corresponding setting in your $HOME/.subversion/config or %USERPROFILE%\Subversion\config. e.g. for my Windows VM I have got:
[helpers]
editor-cmd = c:/emacs-24.3/bin/runemacs.exe
You can add corresponding setting in your $HOME/.subversion/config or %USERPROFILE%\Subversion\config. e.g. for my Windows VM I have got:
[helpers]
editor-cmd = c:/emacs-24.3/bin/runemacs.exe