Yesterday, i was trying to fake glare and bloom in one of my interior renders with many spotlights. Its PITA to do it correctly and manually in PS. Years back, i was using only unbiased renderers where lens effects are part of "package" so i was forced to find another way how to do it. I have got an idea to try VrayLensEffects and....it works!!
Post some of your test here, im curious ;)
PS : Im not 100% sure if it works correctly as in Vray.
Quick testrender below.