1. Copy Makefile, sa-template.xml, security_advisory.dtd, and security_advisory.xsl to your local box or the appropriate directory.
2. Make a copy of the sa-template.xml and name the new file sa-[%y]_%d.xml
3. Edit sa-[%y]_%d.xml accordingly. Heed the comments
4. To create the advisory, type: make sa-[%y]_%d.txt

Note: %y is the last two digets of the current year (1999 -> 99, 2003 -> 03), and %d is security advisory number, unique to a given year.