I’ve tot about 20 recessed cans protruding into an unconditioned attic.  I’m planning on insulating with blown in cellulose after air sealing the attic as much as I can.  Cans are all IC rated – some have CFLs, some have incandescent lamps.  I’ve heard various suggestions on air sealing cans.  Replacing all of the cans with airtight models is cost prohibitive.  I’ve heard a suggestion of sealing any holes in the cans with aluminum tape (the same tape for sealing air ducts).  I terms of “holes” there are retrofit/remodeling cans so these are the attachment spring points. Is that safe?  I’m also planning on sealing the interface between the drywall and the housing itself with acrylic caulk and then covering it all with cellulose.  Is my plan safe from a fire standpoint and/or effective or are there better ways to accomplish this?

I’ve also heard suggestions of building boxes above the housings out of drywall or foam board. I’ve also heard people use “disposable” Styrofoam coolers or minnow boxes. I’m sure that the drywall/foam board box is the best solution but that seems like a lot of time devoted to sealing a can.. Is that necessary or is there an inexpensive commercial product out there for sealing cans that’s reasonably priced? 

I’d love to get any suggestions from insulation contractors out there on how they do this job.