The Unix way to do this is to edit /etc/crontab to get this kind of custom timing.
In E-Smith, this is under the e-smith templates system, so actually create a file:
/etc/e-smith/templates-custom/etc/crontab/10specialscript
With the command you want.
The expand the template using:
/sbin/e-smith/expand-templates /etc/crontab
Get the crontab syntax using 'man 5 crontab'
An example there is:
# run at 2:15pm on the first of every month
15 14 1 * * /usr/local/bin/specialscript
The E-Smith templates system is well-documented here:
http://www.e-smith.org/content/custom/Good luck

Fran