See SSL encrypted messages

If you want to see what is being sent even with SSL turned on, you can install the debug version of the WinInet library. This can log the plaintext version of data exchanged over SSL connections.

Grab an appopriate version from here: http://www.mathies.com/win32tips.html (scroll down to the “Debug versions of Wininet.dll” section). Read the readme for installation instructions. It seems that the instructions were written before Windows File Protection became a feature, so you might have to shut that off to get it installed. This is not for the faint of heart.
[source: virtuelvis.com]