Assuming a preset "Test" already exists, you could do something
like this:
tell application "System Events"
tell property list file (path of file
"com.apple.print.custompresets.plist" of preferences folder)
-- Set duplexing of preset "Test" to wanted
value.
set value of property list item
"com.apple.print.PrintSettings.PMDuplexing" of property list item
"com.apple.print.preset.settings" of property list item "Test" to 2
-- Make sure preset "Test" is selected.
set value of property list item
"com.apple.print.lastPresetPref" to "Test"
end tell
end tell
This may work with your file "com.apple.print.custompresets.plist",
but it will NOT work on mine. A command such as ...
tell application "System Events"
set value of property list item "x" of property list file "y"
end tell
will work without error only if property list item "x" already exists
in property list file "y". If it does not exist, then "System Events"
will error without warning (in other words, your script mysteriously
dies). My copy of "com.apple.print.custompresets.plist" contains only
the value "com.apple.print.lastPresetPref" = "Standard" and will
therefore crash this script.
This is why you need to read the value of the entire plist file into
a record; then concatenate new items to the record; then set new
values; then write the entire record back to the plist file.
Knowing the rules for concatenating records properly is a necessity.
