How to run a perl script

Hi I would like to run a perl script, using rlm_perl, at specific times. For example, when a Stop request comes in run stop.pl, when an interim-update comes in run update.pl. Can someone tell me where to do this. I am sorry if my question seems vague but I am fairly lost. I can write the script I just don't know how to call it. Any assistance would be appreciated. Thanks