try replacing ethernet with bluetooth. it's really a trial by error exercise. good luck.

I have done this with my MBA and MBP and it was slow - fair warning.

Mac OS X 10.5 Help
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Sharing your Internet connection

If your computer is connected to the Internet, you can share its connection with other computers on your local network.

For example, if your computer is connected to the Internet using a DSL modem and has an AirPort Card installed, you can share the DSL connection with other AirPort-equipped computers.

On Windows computers, sharing your Internet connection is sometimes referred to as a “network bridge” or as “bridging your network.”
To set up Internet sharing:
Step 1

Choose Apple > System Preferences, and then click Sharing.
Step 2

Select Internet Sharing.
Step 3

Choose a network service from the “Share your connection from” pop-up menu, Ethernet for example.
Step 4

Select a networking service to share your Internet connection from the “To computers using” list, AirPort for example.

If you share your Internet connection using AirPort, click AirPort Options and give your network a name and password.

If your Internet connection and your local network use the same port (Ethernet, for example), investigate possible side effects before you turn on Internet sharing. In some cases (if you use a cable modem, for example) you might unintentionally affect the network settings of other ISP customers, and your ISP might terminate your service to prevent you from disrupting their network.
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