Until you get a more detailed application installed like PowerBroker, check out the .sh_history logs for each user ID that you are wanting to log. These are located in the $HOME directories and are viewable. It does not give the dates of the command line entries or the related output for those entries, but you can see what was being entered by who. You can also write a little script and put it in cron to echo the date into the .sh_history files and then you'd have record of the entries by the date, at least.
And in case it helps, there is the /etc/security/sulog to that shows user's su activity. Plus the smit.logs show activity that was done through smit. Remember, amateurs built the Ark, professionals built the Titanic.