I am looking for information on this myself.
Update: Figured it out.
Code:
<phrases>
<phrasetype name="Scheduled Tasks" fieldname="cron">
<phrase name="task_yourVarname_title" date="" username="" version=""><![CDATA[Cron Title]]></phrase>
<phrase name="task_yourVarname_desc" date="" username="" version=""><![CDATA[Cron Description]]></phrase>
<phrase name="task_yourVarname_log" date="" username="" version=""><![CDATA[Cron Log Phrase]]></phrase>
</phrasetype>
</phrases>
<cronentries>
<cron varname="yourVarname" active="1" loglevel="0">
<filename>./includes/cron/yourCron_file.php</filename>
<scheduling weekday="-1" day="-1" hour="-1" minute="0,10,20,30,40,50" />
</cron>
</cronentries>