Git still doesn’t have good unicode support so to merge unicode files that git has labeled binary, I wanted to use a visual merger. Finally figured out how to do it — add the following lines to config:

[merge]
   tool = tortoise

[mergetool "tortoise"]
   cmd = \"TortoiseMerge.exe\" /base:\"$BASE\" /theirs:\"$REMOTE\" /mine:\"$LOCAL\" /merged:\"$MERGED\"

[mergetool "p4"]
   cmd = \"p4merge.exe\"  \"$BASE\" \"$REMOTE\" \"$LOCAL\" \"$MERGED\"

If you don’t have TortoiseMerge.exe in your path then you can replace that with the full path (c:/Program Files/TortoiseSVN/bin/TortoiseMerge.exe).