Sudo

You can download SUDO from the SUDO homepage. There are binaries for most OS's.
 * Sudo to another user : sudo -u -i
 * SUDO homepage and Sudo Manual Pages

Setup logs (Solaris)
You have to add the following line in /etc/syslog.conf: local2.debug                   /var/log/sudo.log  Then create the logfile : touch /var/log/sudo.log

 Finally restart system-log : svcadm restart system-log

Setup logging
With logging you can replay sessions using sudoreplay. From the default /etc/sudoers from version 1.7.8p1, here's how to enable logging:

Defaults log_output Defaults!/usr/bin/sudoreplay !log_output Defaults!/usr/local/bin/sudoreplay !log_output Defaults!/sbin/reboot !log_output
 * 1) Uncomment to enable logging of a command's output, except for
 * 2) sudoreplay and reboot.  Use sudoreplay to play back logged sessions.

you can list all the sessions using the '-l' flag or search with parameters after the '-l' flag such as:
 * List sessions run by user millert : sudoreplay -l user millert
 * List sessions run by user bob with a command containing the string vi : sudoreplay -l user bob command vi
 * List sessions run by user jeff that match a regular expression : sudoreplay -l user jeff command '/bin/[a-z]*sh'
 * List sessions run by jeff or bob on the console : sudoreplay -l ( user jeff or user bob ) tty console