(from Lee Monamy)
Example XF86Config-4 for an ELO touch screen:
Section "InputDevice" Identifier "ELO touchscreen" Driver "elographics" Option "Device" "/dev/ttyS0" Option "MinimumXPosition" "300" Option "MaximumXPosition" "3700" Option "MinimumYPosition" "300" Option "MaximumYPosition" "3700" Option "UntouchDelay" "10" Option "ReportDelay" "10" Option "SendCoreEvents" "yes" EndSection
Noteable differences between this and the version 3 config are that you specify a Device, *not* a Port, otherwise you get an error. Also, AlwaysCore from v3 has been replaced with SendCoreEvents.
You must also add to the ServerLayout section, despite that X might say: "(II) XINPUT: Adding extended input device "TOUCHSCREEN" (type: Elographics Touch Screen)"
Section "ServerLayout" Identifier "Default Layout" Screen "Default Screen" InputDevice "Generic Keyboard" ... InputDevice "ELO touchscreen" EndSection