Here's how to get into fastboot:
Install Pantech Drivers, from a command line run:
adb reboot bootloader
Your Burst will reboot and reload into a familiar white screen stating FASTBOOT
Now here's something else I figured out... Not quite sure, maybe APX mode?
With the Burst powered off, if USB Debugging is disabled and you plug it into your computer, some useless drivers are enabled (at least for root purposes):
Network Adapters > Pantech Android MDM WWAN
Portable Devices > F:\
Universal Serial Bus Controllers > Pantech Android MDM RMNET Device
Universal Serial Bus Controllers > Pantech Android USB Composite Device
None of these seem too useful for root...
Now boot the Burst, enable USB Debugging, then power down and plug it into your pc again...
In addition to the above, I now have:
Portable Devices > G:\
Android Phone > Pantech Android ADB Interface Ver1
And with that said, I have a working adb connection from a command line without booting into the device...
Also F:\ & G:\ show up in Windows as removable disks, but they cannot be accessed.
Tried to manually push/run GingerBreak, psneuter, and zergRush, so far nothing will root this device