when in a pinch without any reasonable wifi or internet access, orange gprs is the way to go. at £1/day if you buy an extra with your pay as you go account (dial 450 and then press 3-1-1-1-1) you can get unlimited GPRS up until midnight on the day of purchase. so don't go and by it at 11:30pm unless you are really desperate.
set up your phone with GPRS, you can go to this handy page:http://setup.orange.co.uk/myPhone/Internet/
then once you get through all the prompts, you should be sent the GPRS settings for your phone. for instance, on my nokia 6600, the settings are in:
Settings > Connection > Access Points
note the order which they are displayed, you will need to note that when you connect with it via your mac. for instance, mine is the first one "1".
the other critical step to do while you still have network access is to download some GPRS scripts. you can go to Ross Barkman's Modem Scripts
and downoad the Nokia or Sony Ericcson GPRS scripts. those are the ones that i've tried and had good results.
after extracting the download, you'll need to drop them into "/Library/Modem Scripts".
after that, you'd want to pair your phone with your mac via bluetooth. once you do that, in your network preferences you should be able to select the Bluetooth interface and have the following options (for a nokia 6600):
choose Nokia GPRS CID1 for if your access point appears to be the first, or CID2 if it is the second, and so on. you can experiment with the 57.6K scripts too, but it wasn't necessary for me.
remember to put in "None" in the telephone number, and you don't have to fill in any of the account name and passwords.
and in PPP options:
remember to switch off "Send PPP echo packets", otherwise you'll find your GPRS session disconnecting every couple of minutes.
once that is all done, you should be able to go to "Internet Connect", select Bluetooth and dial out.
for debugging purposes, you can enable "Use verbose logging" in the PPP options and open up "Console.app" and look at /var/log/ppp.log for more information.
a final note, for sony ericsson phones, they setup access points slightly differently, so instead of the phone number "None", you must put in the name of the orange access point, which in my case is "orangewap".