Just because I don’t like Windows Mobile doesn’t mean I should deprive you of the awesomeness that is Windows Mobile 6. If you own an AT&T Treo 750 and want to upgrade to the latest crap version then listen closely…
Installation and Upgrade Guide
• Plug the Treo 750 into a power source
• Load software update onto your miniSD card (CHEEIMG.nbh file). Insert the card.
• Press and hold both the PTTApp Button (lowest button on left side of device) + Pin Reset (next to miniSD card slot). You no longer need to hold the Windows key as well. You will be prompted to press the End key to start the update. This step takes about 10 minutes to complete.
• Hard reset the device when prompted. To hard-reset, hold the End key while pressing the pin reset button. Answer “yes” to “Erase all data” prompt.
• To verify the software, hold the Down-Arrow while pin-resetting. You will see:
o Firmware: R 1.47.25.00
o ROM: D 1.25
o Keyboard: U 26
• The Bootloader can also be confirmed by holding down the PTT button and pin resetting (without the updater miniSD card inserted)
o SPL: SPL 0.24
Who wants the ATT WM6 rom?!??! [XDA Forums]