How to audit data flow runs

What I would like is to audit each run of each data flow.
Logging looks almost good enough, except that it will only record the supported system variables, and I want to record some additional info -- at least a user package variable that (I know) specifies what the affected time period is (of the data being flowed).
I could make a custom component (a), which writes an audit record to an audit table, and records the identity key generated, and then attach that identity key as a new output column, so that I could run the data flow through this data flow component, to attach the audit id to every row.
I don't know how to get access from within the custom data flow component to interesting system variables (eg, computer, date the data flow started, execution id...) ?
Also, I'd like to do an update at the end of the data flow, to store the completion time (and whether success or error) back to the same table where I recorded the audit event -- for which I could use that key I got when I added the audit row -- maybe I want to record it into a package variable for later use from the component (a) which created the row.
Does anyone know how I can hook the data flow completion (optimally, hook both success and failure) -- eg, the "OnPostExecute Event" -- I don't know how to write code or script and get it to run at OnPostExecute time, which sounds like the desirable time for me?
Or anyone have better ideas of how I could accomplish my goal here (which is to record data about each run, data consisting of not only the system variables available to the logging, but also at least one user component variable -- and preferably to record this data to an audit table, and then supplement my dataflow with the id of this audit record, so that all stored records point back to it)?
Perry,
You're on exactly the right lines in using the OnPostExecute event handler to achieve what you wnt to achieve here.
I've written a small demo of using event handlers in exactly this situation. You can pick it up from here.

There's a downloadable demo in there plus explanations of exactly what's going on. I hope its useful to you and if its not, please let me know.

-Jamie|||Mark has done something we could use to achieve this. Have a look. It's cool. It works on the similar principal as RowCount, but you can set event hanlder to do the auditing.

http://markiehillmsis.blogspot.com/

Thanks
Sutha