Here you all are, it took me a while to find it but the settings you need to use your as a GPRS modem on your laptop are:

Follow the instructions here:

[User] HOWTO: Use BlackBerry As Modem For Laptop!

.....use *99# as the number to dial

....and when you have to add the "Special Configuration Step" add the following line:

+cgdcont=1,"IP","orangeinternet"

Then when you connect leave the Username & Password blank. If you are using BES v4.0 then there is no need to edit any settings to make it work. I'm using 8700F handsets by the way.