I found the Alltel USB drivers and QuickLink software.
The software allows you to use your phone as a modem.
software.alltel.com
Do not select Windows 7 as your OS. If you have 7, just use Vista.
I am running Win7x64 and the x86 Vista drivers installed without a problem.
I was able to run the software and get online using my phone.

The specs in the software showed 280kbps max. I pulled almost half that at 5 bars of signal on EVDO.

I tried using Bitpim but was unable to get it to work. My phone hasn't worked with Bitpim since the first time I used the program (and that was on a Server 2003 system {WinXP compatible})