First, get Fiddler.

Modify your %USERPROFILE%\Mercurial.ini file to include the following:

[http_proxy]
host =127.0.0.1:8888

When running Fiddler, make sure Capture Traffic is turned off (press F12 to toggle Capture Traffic on and off; this is a bit odd, but it’s needed or it will capture all traffic). Fiddler should now capture mercurial traffic.

HTTPS

If connecting to Kiln over HTTPS, you may wish to decrypt HTTPS traffic. Go to Tools > Fiddler Options, HTTPS tab. Make sure that “Capture HTTPS Connects,” Decrypt HTTPS traffic,” and “Ignore server certificate errors” are checked.

When running mercurial commands, you may need to use --insecure if you’re using Fiddler to capture https traffic.