The manual is here:
http://www.grsecurity.net/gracldoc.htm
though it does not cover grsec2 (some of the configuarion differencies are covered in the acl file from gradm2-package).
However I couldn't find what you are looking for there, so I'll give you a hint: grsecurity logs through syslog-messages, so you should configure your syslog daemon to handle kernel messages. Read the man pages for syslogd and klogd.