Your setup guide is here, which gives detailed setup instruction:
http://www.lexmark.com/publications/pdfs/8300/eng/setupsh.pdf
Your user manual is here:
http://www.lexmark.com/publications/pdfs/8300/eng/ug.pdf
The technical support page, with contact information is at:
http://downloads.lexmark.com/perl/downloads/downloads.cgi
Unfortunately, there does not appear to be an automatic place to download the software from, but you should be able to obtain it from support. If you just want to get the printer operating, choose the proper operating system, etc., and download the driver, following the other setup information. Then you can follow up at your convenience for the actual software.
If this information assists you in resolving the problem, please take a moment to rate the solution at a "FixYa" level. If you do not feel that you can rate at a "FixYa", please post back with more information regarding what has occurred subsequently and/or more details regarding the situation, and I will gladly help you until we have reached a definitive solution. Thank you for using and rating FixYa!