If you want to try scripting it into Cacti or something like that, you can do an SNMPWALK on OID .1.3.6.1.4.1.14823.2.2.1.5.2.1.4.1.19
The result is a big list of OID instances, with OID ending with a different number. Example:
Walking .1.3.6.1.4.1.14823.2.2.1.5.2.1.4.1.19. (wlanAPStatus) on xxxxx | | |
1.3.6.1.4.1.14823.2.2.1.5.2.1.4.1.19.0.36.108.199.201.53
| up (1) |
1.3.6.1.4.1.14823.2.2.1.5.2.1.4.1.19.0.36.108.199.229.34
| up (1) |
1.3.6.1.4.1.14823.2.2.1.5.2.1.4.1.19.0.36.108.199.229.36 | up (1) |
1.3.6.1.4.1.14823.2.2.1.5.2.1.4.1.19.0.36.108.200.127.30
| down (2) |
So what those last six numbers are is a decimal representation of the MAC addresses of the APs. Looking at the first one, it would give me a MAC address of that WAP as 00:24:6c:c7:c9:35 (decimal 00:36:108:199:201:53)
You can pull that whole thing in from each controller, and parse it to look for the "down (2)" and monitor that way. It's a bit clunky but it might do what you're looking for if you can integrate it into something else. (Sorry for the formatting on the tables, didn't paste well.)