The LAN cable is so you can control the document camera via the phone or touch pad.
If you aren't able to do that, I imagine you could plug the document camera's output into the PC/presentation input (where you would usually plug in a laptop) but you would then need to control the document camera via a remote control or buttons on the unit itself, rather than being integrated into the TX 9000's controls. You also wouldn't get any monitoring or feedback via the WebGUI etc, as the TX9000 would just think it's a regular laptop input.
