CaNiBuS,
the same 176 option, but starting with 2.0 firmware (or maybe later, i tried 2.2) phone tries to access http first, then https, then tftp server at the specified tftp address. so you don't need to change dhcp settings, just set up http server on the machine where tftp server now is, and upgrade phones' firmware. or you can upgrade phones first, then try to set up http server, it doesn't matter. phone will boot up a bit slower, but not much.