Create the file ediff.bat with content:
SET "client=c:\GNU\emacs-24.2\bin\emacsclient.exe" SET "mine=%1" CALL SET mine=%mine:\=\\% SET "base=%2" CALL SET base=%base:\=\\% START /MIN %client% -c -e "(ediff""%mine%""""%base%"")"
and the file emerge.bat with content:
SET "client=c:\GNU\emacs-24.2\bin\emacsclient.exe" SET "mine=%1" CALL SET mine=%mine:\=\\% SET "theirs=%2" CALL SET theirs=%theirs:\=\\% SET "base=%3" CALL SET base=%base:\=\\% SET "merged=%4" CALL SET merged=%merged:\=\\% START /MIN %client% -c -e "(ediff-merge-files-with-ancestor""%mine%""""%theirs""""%base%""nil""%merged%"")"
Then configure Tortoise SVN to use the previous files as external commands. For example, if you saved the files under the directory C:\Users\Dupont\Scripts\ then, in Settings>External Programs>Merge Tool, you can set:
C:\Users\Dupont\Scripts\emerge.bat %mine %theirs %base %merged