If you can pair them up then you're 80% success.

Did you join PAN on client side? It must be done after pairing up. You may see bluetooth has lots of function, it doesn't activate all functions by default, you need to trigger it manually on client side.

Also, depends on some client platform, you need to activate the script *after* client pairing up and join PAN.

In your case, please follow:

1) Pair up Bluetooth
2) Join Bluetooth PAN on client side
3) Choose Internal connection manually on N900
4) Activate the script on N900
5) Setup DNS on client (as shown the the procedure)
6) ping yahoo.com, or browse the web directly on the client side to see it works

Hope this help.