I did this a few months back.
SuiteAnswer 75940 doesn't really show inventory aging, it shows inventory affecting transactions by bucket (30/60/90 days)
I did a proper inventory aging report, showing qty/cost age distribution.
However, you also say "basically what we had at the start and end of each month". That sounds more like a inventory valuation report (aka stock status report), just for each month.
Could you confirm which you're after, or elaborate on the requirements?