you create a new connection in Remote Access. Better still you create a new Profile (or Environment, not sure how its called in english OSs).
As a modem you choose Nokia (the one you have) in the modem control panel. I think this is alreadey on the Book. I have a Siemens and I had to search the net for a modem description, but I found one and put that into the modem description folder. The other stuff is the same as for a "normal" dial-up PPP-connection, just the modem is different. Your phone needs to have a modem build in, but all newer models have (your Nokia seems to have on I guess, sicne the 8000er series are the top-models).
Then you fill in a mobile provider phone number in Remote Access, and dial. Here in Germany every network has mobile dial-up numbers, check for that on the website of your network provider.
Then it connects (with normal GSM network it won't get faster than 9600 bps, you need a GPRS capable phone an network to get up to 56.000). And the rest ist the same. Just check/send your mail. It's slow but for emails enough.
It worked for me all over Europe. I was able to check/send mail from the North of Sweden, where there is just forest, but still GSM coverage. That's cool.
Hope this helps. If you need mor info, ask. It's fairly easy and I want to have (I need) this in X!