Does anyone know if it is possible to enter tones to enter passkeys, or erase messages in voicemail from the D3 screen during a call?

No dice as far as I can tell. You have to use the keypad on the phone itself to enter that information. a bit of a pain but it does work. On most systems you can enter in your password into your voicemail speed dial so you can at least hear your messages without entering anything extra.