I've just published a major revamp of the DB2 for Linux HOWTO document, and it's available for reading/downloading from:
and the PDF is directly available at:
This update covers DB2 Express-C 9, and includes instructions for the latest Linux distributions. All comments are welcome, either in the DB2 Express-C forum, or through an email to email@example.com. Please check it out and let me know if it helps you, or needs additional coverage, or anything else!