In order to have Android 2.2 Froyo on HTC HD2, we need to flash to newer radio ROM like Leo_RADIO_2.12.50.02_2 that I am using right now. Custom Windows Mobile ROM requires latest radio ROM in order to work too. Same apply to custom Android 2.2 Froyo ROM. CustomRUU for HTC HD2 is the tool that uses to flash the radio ROM. It will perform ‘task 32’ instead of a ‘task 28’ after flashing an .nbh. And it will not format device if just flash a radio or a splash screen.
Download CustomRUU for HTC HD2 here.