[Logician]

You'll have to create a table for this and update table data in showthread.php (and other relevant files) and record data like visit time, visiting member id, visited thread etc.

Then you have to have an individual script which will compile data from this table according to your wishes to see your statistics. This script (or another one) should be able to clear the table data whenever needed so that you table does not get too large.

This hack is not a simple code change, you have to commit sometime for this. Moreover remember that you'll have 1 extra SQL query whenever someone visits a forum/thread, decreasing your board performance. Good knowledge of PHP is needed to code this hack..