I\'m setting up a git environment on Windows XP (msysGit 1.7.11, TortoiseGit 1.7.14) and trying to achieve following points :
No tweaks needed.
Just make TortoiseGit point to the same ssh client used by git itself, see the screenshot:
This should be C:\Program Files\Git\usr\bin\ssh.exe in latest version of Git as mentioned by Aleksey Kontsevich in the comments.
C:\Program Files\Git\usr\bin\ssh.exe