Yeah. I think I gave a bunch on dr hashmans stealth attic grow, but my advice is pretty much insulate as muich as you think you need to, and then insulate some more, because temperature control is a fucking BITCH up there. If you don't have a window to hang an ac out of, or central air, plus a good spot to exhaust, don't even bother.
Honestly cellar grows are easiest because the cool ground is insulating, but when your water heater explodes, you have to clean up beofre the plumber gets there, ya know?