In case of Client-Server connection, the Printing Method is stored in the Tools > Configure > Printing Methods section (login as admin).
In case of server older than DeskPack 12.2, you should be able to find a printingmethods.dat file in \\SERVERNAME\bg_data_custom_v010\dat\ printingmethods.dat
In case of standalone DeskPack installation, you can find the printing methods in the Illustrator or Esko Plugin Preference file (depending on Adobe® Illustrator® version) AND also in the Illustrator document dictionary (so available in the file itself). The Esko Plugin Prefs file can be found in /Users/<current user>/Library/Preferences/Adobe Illustrator 17 Settings/.