So did I, here's the notes I wrote so I never forget how to use it:

```
Git diff support (note below):
http://www.scootersoftware.com/support.php?zz=kb_vcs#gitwindows

Must use:

# External Visual Diff/Merge Tool
[diff]
    tool = bc3

[difftool "bc3"]
    path = "C:/Program Files (x86)/Beyond Compare 3/BCompare.exe"
```