Yes, it can include private flying, and in fact it can include any loggable time on aeroplanes, although I can't remember the exact rules re. non-aeroplane time.
There are a number of other requirements to be met, too. One of these is for 500 hours of multi-crew time. Although I don't think it's actually a requirement for this to be commercial, there aren't too many people are going to be able to get 500 hours of private multi-crew time
FFF
--------------