In PHP you can do this with the following PHP function:
set_time_limit(30);
This will reset the script time limit to 30 seconds, this is the default. You can extend this to a larger amount of time and have it at the top of the page, or you can add it in like this inside of the loop. Once in the loop it would extend the time limit of the script by another 30 seconds for each address.
Here is the php page that discusses this:
function.set-time-limit.php