Plug the iPhone into the Mac using USB. This will charge it while the phone offers tethered service. (Bluetooth should also work but will drain the battery quickly).
Turn on Personal Hotspot
On the Mac
System Preferences>Sharing>Internet Sharing
Share your connection from : iPhone USB
To Computers Using: Wi-Fi
Wi-Fi Options …
- Provide a network Name: “My Tethered Network”
- Select a Channel: something unique such as 36 is better than default 11
- Security: WPA2 Personal
- Password: something 13 characters long exactly and same again in Confirm Password.
Click “On” for Internet Sharing –
On other devices you should now see the “My Tethered Network” and be able to connect from other devices.
Make sure to set your sleep appropriately on the Mac, otherwise it may go to sleep mid session.