Add alerts for calculate metrics (by line, not total)

[#1]

I would like the chance to add alerts to calculated metrics in a given report on a given line. Lets says I have a report that shows various lead forms, and I would like to add an alert that triggers when a certain form exceeds a given percentage on the submission rate (calcualted metric), this is not possible in SIteCatalyst today. The closest I can get is to have an alert on the calcualted metric itself, but this would then include ALL lead forms, and be for the total submission rate, and not per form.