Lexmark offers deb packages of linux drivers
Go to Lexmark/downloads (http://support.lexmark.com/index?page=home&locale=EN&userlocale=EN_US&segment=DOWNLOAD)
Enter your printer model number, linux (S300, Ubuntu)
Extract it, run it from the terminal as sudo
(sudo sh lexmark_inkjet_09_driver_1.0_1.i386.deb.sh)