You get an IMA light because one or more of the cells are flat sooner than the others, triggering the BMS to report this and shut the pack down, because the pack is only as strong as the weakest cell, just like a chain.. bla bla.
From what I know about the Insight battery, you just need a constant current charger like any cheap nimh charger, but souped up to a higher voltage for lots of cells in series. The "balancing" would work because nimh cells (unlike lithium) stay the same voltage and convert the excess energy to heat when they're full, allowing the "low" cells to catch up and also get a good fill back.
I could easily design something simple, but I assume theres plenty of designs already on the web..
In the crudest form, you might get away with just a DC power supply and (a few) 12v light bulbs in series as current limiting resistors.
[edit] read the link you posted to the other forum, I like the charger/discharger they linked:
http://dmr-architect.com/~locouki/In...ischarger.html even if you skip the discharging bit, that should be easy enough to build.
In the long run, you might need to find the bad cell(s) and replace it (if nothing else, with better used cells), but in the short run, just charge it and don't push it too hard.