Using table trigger to store application usage (AS/400)

Hi all!

We're trying to find a way to track usage of interactive and batch applications in preparation for upgrade from XE to 9.1 For batch versions this would be easy (copy submitted jobs every night) but there is, to my knowledge, no way to track usage of interactive applications?  (how often an application was run / last execution date)

This is why we're looking at solving this by using table triggers. Has anyone done anything like this before and would like to share thoughts/comments on this? I was thinking to drive the trigger from the the versions table and update a custom table with usage stats (Application/Version/Number of times run).  Or is there, maybe, a way to do this without modification?