(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