I've been trying to boot the S90 (which does say Windows XP embedded) without luck. It will seem to reach out to the DHCP server and is offered an ip address (according to the OS X Snow Leopard Server server log) but it does not seem to accept it. If the terminal does get to the log in screen it just hangs there. I've tried the Administrator/Administrator default with no luck.
I've also tried to build a USB key using the USB Firmware Tool 18.104.22.168 and firmware file 9S92_S607_512 but in no case does pressing P during the boot sequence cause the system to boot from the USB. I have tried renaming the 92 part of the filename to 90, setting up with or without BIOS/CMOS included, leaving the partition intact, etc. No difference.
I am at a loss for what to try next. Any suggestions?
The S90 does not support the USB firmware tool. You will neeed to use the Wyse Simple Imager toola available at www.wyse.com/downloads under the RETIRED section. Make sure you read the documentation and follow the instructions, as both the S90 and WSI are obsoleted products and no longer supported. The information that is available with WSI was the last one tested. Good luck.
... but in no case does pressing P during the boot sequence cause the system to boot from the USB. I have tried renaming the 92 part of the filename to 90, setting up with or without BIOS/CMOS included
Not sure if I understand correctly, but... Did you check the BIOS is setup to boot first from USB? If not done yet, try pressing the Delete key while booting (you might need to press the delete key _before_ you plug in the power) so you can access the BIOS screen. You might need a password to change the BIOS config, and the default one is Fireport. Good luck!