I've personally not used VNC on the ICS7750, but the best method to install the OS remotely or without a console access is to use VNC, which is supported by Cisco.
If you are already using WinOS2000.2.4, you should have c:\utils\vnc subdirectory, and you can
install the application from there. Otherwise you can download and install VNC from
http://www.realvnc.com/download.html
Please make sure you have updated the Windows OS via the System Manager updates from CCO:
http://www.cisco.com/cgi-bin/tablebuild.pl/ics7750-rel260
Additional info:
May I use Terminal Services, VNC, or ILO to install the operating system on this server?
http://www.cisco.com/univercd/cc/td/doc/product/voice/iptel_os/install/os200024.htm#356020
