php.ini

At the beginning of the script, type in the following command.

set_time_limit ( int $seconds )

You can read more about it at http://de3.php.net/set-time-limit.

how do you write the ini set when needed?

The general answer is that it depends. On my servers I have kept it to 30 seconds as default. But in the scripts which I know will take long then I reset it to whatever number I want at the beginning of the script.

On servers with low traffic, the timeout won't make big difference, but on busy servers, it is recommended to have the script finish its job asap so it could handle more users. So having the shorter timeout is recommended on busy servers.

HTH,
Ketan