I've seen this trick used before on a separate blog:
Create a config file for logrotate, let us call it
Then from cron (may need to be in root's crontab depending on the permissions and ownership of the log files), a crontab of:
0 */2 * * * logrotate -f /path/to/httpry.conf
EDIT: to describe crontab editing for OP
A crontab can be created for your user account by issuing
crontab -e. If you want to edit a specific user's crontab, as root:
crontab -e user or on some systems
crontab -e -u user. You will then be put into an EDITOR which will allow you to edit the crontab, and wrting the file out will check the crontab for errors (giving an error if incorrect) or installing the crontab if correct.
rotate 84 option, as he describes in the blog, is to keep a weeks worth of logs. (24/2 hour intervals = 12 logs per day, 12 * 7 = 84 .. or 1 weeks worth of logs).