First off the oven thing does work but you might want to go down to the junk yard and get an extra light housing for a test run on it.
Once you got your test run housing fire up your oven to about 225 degrees. Make sure that if your oven needs to preheat you let it do so. Next take a cookie sheet or pizza pan and put the housing on it and slide it into the oven.
Note ( depending on which part of the light you are keeping/ i.e. you want to keep your housing but not the lens, then you would put it into the oven on the sheet with the lens down. Visa versa if you want the lens.)
Check on your progress of reliquifing the glue every 2 to 3 min's. It normally takes a total of 10 - 15 min's but, it is always best to check it over short periods of time so you don't over heat it and melt your piece.(thus the reason I say try it first with a spare.) In order to check the progress the best way that I found is to take a long, thin-small-headed flat head screwdriver and, wedge it between the lens and the housing where the little clips slide into the housing. By doing this it will give the lens a smother surface where it can slide out.
Note ( your best bet is to do this to one clip at a time. Once you have one pulled away from the housing then move the scerw driver to the next clip.)
Now when you're pulling on the lens you will need to pull kind of hard so that it will strech the bonding glue. But if you hear a cracking noise stop there and reheat. If you keep pulling while it is cracking then you will snap the lens. Being as in you want to keep the lens that is. If you're not looking to keep the lens then I say: Snap away and use the screw driver to pry out the little parts that are still lodged in.
When you are pulling the lens from the housing it makes it a little easier if you use a second screwdriver or knife to cut the glue strings that are streching from the lens to the housing.
After enough heat has been applied to the housing the glue will give way and, you'll be able to slide the lens out. You can use the screw driver or what ever you find to remove the rest of the glue.
Once you have your lens removed take the new lens and cut it to the right size to fit. When your lens is cut and you check to see that it fits snugly the best adheasive that I've found to use is "3M Plastic Emblem & Trim Adhesive Glue". It will make it water proof and should hold firmly for you. You can get it in most auto places. I got mine from Meijer in there auto section for about 4 bucks.
When your lens is set and you have glued it in firmly reattach and you are good to go. Hope that's detailed enough instructions for you guys. If you got a question just let me know.
S.W.Flame
(Ryoko)