im my opinion id put the stock tails back on. but anyway, if you want to get them apart you will have to heat them in the oven. i put headlights in for 10 min at 200. id try like 7 or 8 or less. just be sure not to melt or warp anything. If you dont want to do that, than buy modelmaster spray paint from a hobby shop and spray that on a few coats until its dark enough. i used that on my tails and it looks good and hasnt faded or anything after about 2 months. testors paint also works pretty good.
and if you want to take them apart and want to be sure not to melt anything, buy a heat gun or try a blow dryer. they may work. you just have to heat up the glue enough to let you pull them apart. youll prob need a flathead screwdriver and you will need window sealant to seal them back up. be sure to seal them good or they will get condensation in them and look like ass.