How to take apart headlights?

I just have a quick question for anyone who knows the answer. What temperature should the your oven be at to melt the silicon seal around the headlight housing without causing damage to the headlight itself? And how long should it be in there for?

I had done this on my old civic below in the pic works great.

Tools needed
- 2 Headlamps
- Silicon
- Hairdryer
- Access to an oven

. . . .. . . . .
1. Preheat oven to 325-350 degrees
2. Pull out a baking pan and lay the light housing on there
3. Put it in the oven for about 2 minutes
4. Use the blunt side of two butter knives to pry apart the housing from the cover
5. Use a hair dryer to keep the piece warm
6. Paint or whatever you want to do
7. Scrape off all the old silicone on the housing and cover
8. Put a new bead of silicone down
9. Hold the housing together and let the silicon set. (use several loops of tape around it if you don't want to hold it for a lilttle while)
10. If you want to be extra certain that there are no leaks, run a little bit of silicone around the seal to be double sure.

*** Another option is to use a heatgun in place of the oven and hair dryer. A bit less risky but more time consuming. ***