Just in case anyone else is interested. I managed to get alerts working for the external temperature probe on an APC UPS. First, with the Custom MIB Poller Wizard, I created a custom MIB Poller to poll OID 1.3.6.1.4.1.318.1.1.10.2.3.2.1.4. I named it ExternalTemp and put it in a group named APC. I used a MIB Value Type of Raw Value with a Type of none. I assigned all my UPS's to the Poller using the Assign button in the Custom MIB Poller Wizard.
Then I created an advanced alert set to trigger for any custom node poller when the poller name is equal to ExternalTemp AND Status is greater than or equal to 80. (I have my UPS's set to use farenheit, not centigrade). The reset is identical except it triggers when Status is less than 77.
Lastly, my alert message is "Warning ${Date} ${Time} - ${NodeName} is ${CustomPollerStatus.Status}". Remove the quotes of course. The reset message is nearly identical. The output of the message has a zero in the node name for some unknown reason but, I can live with that.
