You can insert dynamic attributes that are periodically updated from a script. Here's an example of what you put in the HTCondor configuration file to periodically call a script:
{code}
-STARTD_CRON_NAME = CRON
+STARTD_CRON_JOBLIST = CRON
CRON_JOBLIST =
CRON_JOBLIST = $(CRON_JOBLIST) kernel
