So, I use svnX on MacOSX and I find DiffMerge a much nicer application than the default FileMerge, but I couldn’t get it to load. I was getting some spurious error about a missing .sh file:

Can’t find tool ‘diffmerge.sh’ required to use DiffMerge

Anyway. I found this file in the following folder:

/Applications/DiffMerge.app/Contents/Resources/

And I simply copied it to a folder within the path env,

cp /Applications/DiffMerge.app/Contents/Resources/diffmerge.sh /usr/local/bin/

Sorted. Don’t forget you actually have to change the application preferences.