Its was provided in one of the patches. You need to look in your Steam directory:
<Your Install Drive and Path>\Steam\steamapps\common\il-2 sturmovik cliffs of dover\records\
then to see them in game, you need to copy them to your user folder:
C:\Users\<Your User Name>\Documents\1C SoftClub\il-2 sturmovik cliffs of dover\records\
*Win 7 example
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