330062 Use Blackberry 8900 as modem

I have a blackberry 8900 on Orange UK which gives me an unlimited GPRS internet data plan. I have a MacBook with Mac OSX 10.5.6 I want the MacBook to use the Blackberry 8900 as a modem via bluetooth for times when I have no internet access (e.g. no wifi on lan). I require step by step instructions on how to achieve this including any modem scripts needed (they are out there already!). I don't just want a a copy and paste of online guides, links to threads - I want you to read the guides, distill the information and write me a step by step guide so I can complete this without too much effort.