I just got a second email from philips as follows:

Philips Semiconductors answer:
Sorry for the initial answer, that is what happens when we get a little overloaded. To answer your question, the prescaler divisor is the 10 bitvalue in the TPCR2L/H register + 1. The +1 ensures that there is not a divide by zero condition. However, you are correct, this is not in the users manual. I will suggest they add it in future versions. Also, you can thank your friend in the US for having us re-look at this.

So basically it operates in the same manner as the 4bit PLL prescaler. Nice to know they are thinking of adding it to the user manual. Let's hope they update their FAEs.

Also special, thanks to Erik for pursuing this on my behalf.

Time to get coding.

Ian