Illustrator comes with supplementary PDF presets (.joboptions) files, which are installed in the Extras folder in /Documents and Settings/All Users/Documents/Adobe PDF (Windows) or /Library/Application Support/Adobe PDF (Mac OS). You may also receive custom PDF presets files from service providers and colleagues.
Double-click the .joboptions file.
Choose Edit > Adobe PDF Presets. Click Import, and select the .joboptions file you want to load.