Are you asking where to define the DTMF functions ?     Look in /etc/asterisk/rpt.conf

If you need the commands, (i.e. COP,3) take a look here : http://www.allstarnode.com/viewtopic.php?f=5&t=8

The source code for app_rpt is at /usr/src/astsrc/asterisk/apps/app_rpt.c .