3 choices:
1. Get an updated version of the script that does not use deprecated features.
2. Find the source of the errors and change the code buy using pregXXXX functions, etc
3. error_reporting(E_ALL & ~E_DEPRECATED); at the top of the entry to the script (often index.php). Just hides the warnings for now. But since they are just warnings, there should be no harm. If PHP ever removes eregi, etc, then you will have to revert to #1 or #2