I posted this on Sprintusers and thought I'd share it.

http://www.sprintusers.com/forum/sho...74#post2157274

How to diable the NAI on the M1. (I forgot where in QPST you'll need the MSL, but trust me you'll need it).

1) Find out your MSL (by using CDMA Workshop or calling Sprint and asking. Or heck, it's the "Secondary 6-digit code" when you activate it online.
2) Download QPST (I used Build 301) and install it. I found QPST on RapidShare.com
3) Once you have QPST installled, open "QPST Configuration"
4) Click "Add New Port" and enter whatever port your M1 is connected to. You can find the port it's on by going into Windows Device Manager and looking at "ports." When you find the port, enter "COM" plus the number. For example, mine was "COM5."
5) Once you have that set up, click on the "Start Clients" tab and go to "Service Programming."
6) Once in Service Programming, go to the "PPP Config" tab.
7) In the PPP Config tab, there are three subtabs. Go to the "AN" subtab and copy whatever is in the "User ID."
8) When you have the User ID copied, go to the "Um" subtab and paste the User ID into the empty User ID box.
9) Click "Write to Phone" and Wa-laa, you should be able to tether with the M1 now

Install the Sprint Mobile Broadband software from sprint.com/downloads and install it. Before I did this hack, I would get an "Error 67; User ID could not be verified." After doing this, the M1 connects to the Sprint network with no problem. (Just to be sure, I want to remind you to make sure you have unlimited data on your plan before you use this).