Hi Shen,
Yes, by using the API, you can activate the cron when you start your scripts.
About the frequency, currently we offer only cron execution every 5 minutes.
If the timeout of your script is short (< 25 seconds) you could also use Webcron monitoring to launch the script, with a frequency up to every minute. Keep in mind that monitoring will not send you an alert when 1 execution fails, it will only send one if 2 consecutive fails are found. If this is ok for you, you can start using it right away, since the monitoring API is already available for members.
See
http://www.webcron.org/api for more information.
Let me know if you need more information or help implementing this.
Regards,
Bastiaan