Sorry I'am a bit late to respond to this topic but I was on vacation last week.
Another method of monitoring the IBM 3494 on AIX is to use the mtevent
command which is shipped with the atldd driver. We run this command as
backround task and redirect the output to a file which is monitored by a script.

For example when an intervention is required you get the following message:

mtevent: Thu Oct 29 10:13:30 1998
An unsolicited attention message has been recieved.
Request ID: FF1B8502
Operational state change
   operational state....Automated Operational State
                        Intervention Required

if a mount fails:

mtevent: Fri Oct 30 11:25:17 1998
A delayed response message has been recieved.
Request ID: 150A4E00
Demount complete
   completion code......Failed - Volume misplaced.
   operation flags......00
   category.............0000
   operation volser.....J70288
   vision read volser...

if a device is not available:

mtevent: Fri Oct 30 11:31:00 1998
A delayed response message has been recieved.
Request ID: 150A4E07
Mount complete
   completion code......Failed - Device no longer available.
   operation flags......00
   category.............0000
   operation volser.....J70465
   vision read volser...

Sorry, but IBM provides no documentation of the output.

Hope this helps!

Othmar