Displaying / graphing TimeWorked per transaction and not per ticket

My users are regularly keeping tabs (via the timetracking extension) on how long they spend working on a ticket. Tickets tend to be rather long, spanning several weeks (with weekly reviews and performance evaluations) and therefore, we’re struggling to find a good way to see how much time was spent working on tickets each week.
RT’s default graphing (grouping by “started - week of year”, calculating total time worked) just takes the lump sum of TimeWorked for a ticket and displays it in the week it would appear due to the grouping (in this example, the week it was started in). However, time was spent working on the ticket in any or all of the subsequent weeks, skewing the amount of “ticket time” that’s displayed in these weeks.
Is there any way to achieve this with stock RT searches / graphing? Is there a way around this? I saw some old threads from 2009ish that were basically querying the database directly, but I’d really like to have a way of doing this from inside RT.

In a transaction search (available in RT 5.0.0 onwards) you can add a field of “TimeTaken” for each transaction, as well as the date that the transaction was created on. Is that the sort of thing you’re after?

Yes, that looks like the type of information I am after, however transaction searches don’t seem to be graph-enabled, meaning I can’t seem to create graphs from the result page.