The Manual above will tell you specifically what you need, how much is needed, and will show you how to do the procedure correctly, including pictures and torque specs. The cost of the book was easily recouped on my first oil change.
For the parts not available off the shelf, call up your closest Mc Dealer and make a friend in the parts department. They will gladly sell you the parts needed for your annual service (should be an oil & filter change, brake fluid flush, 2 new air filters and a windshield wiper blade IIRC).
One last thing. Once you have serviced the McLaren yourself, you will have to visit the Authorized Dealer because at this time only they can reset the Service Reminder displayed in your instrumentation cluster.