I appreciate that SourceTree is just a front end for git (or mercurial), but what I was hoping for/am imagining is a config option to use a different diff tool.

For example, the most common solution for diff/merge of utf 16 that I run across on the web is to use vimdiff as described in the solution here:

http://stackoverflow.com/questions/777949/can-i-make-git-recognize-a-utf-16-file-as-text

If SourceTree does not already have an option to use a different diff tool, I suppose I am requesting that a configuration be added to SourceTree to use a different diff tool.