All you need to do is map an event that you get however works for your device.
1. Create the mapping for /Heartbeat
2. Set evt.component to something that makes sense
3. Set evt.timeout to the frequency you want the heartbeat.


An example per Chet Luther:
Let's say you send in a trap with an OID of .1.3.6.1.4.1.654321.1. You  
would create an event mapping in the /Heartbeat event class called  
"Automate6Heartbeat" and set its event class key to that OID. Then  
within the transform of the event you'd enter the following.

evt.component = "Automate 6"
evt.timeout = 600

That's all there is to it. If 600 seconds go by without receiving this  
trap Zenoss will automatically create one of those "heartbeat failure"  
events with the device set to the device sending the traps, and the  
component set to "Automate 6". This heartbeat checking is performed  
within the zenactions daemon which cycles once per minute. You can  
look at the heartbeat table within the MySQL events database to see  
what heartbeat Zenoss is currently monitoring.