Here is the step by step for the Atrix, posted originally by Fixster. There maybe slight
Steps 1: Browse to Menu>>Settings>>Wireless & Networks>>Mobile Networks>>Access Point Names.
Steps 2: Tap ‘Menu’ and select ‘New APN’.
Steps 3: Enter the following APN settings:
Proxy: ** Leave Blank **
Server: ** Leave Blank **
MMS Proxy: wireless.cingular.com
MMS Port: 80
MMS Protocol: WAP 2.0
Authentication Type: ** Leave Blank **
APN Type: ** Leave Blank **
After you've created the APN, you switch to it, then enable your hotspot. After you get the notification that setup was successful, switch back to the original APN.
Just a cursory glance in the Infuse settings revealed that unlike the Atrix, there are no radio buttons to select your current APN, so I'm not sure how that part works here.
EDIT: Since I am a noob, I can't post links, and there are instructions here that contain links. Just remove the ().