E46 LED Tail-Light Disassembly

I'm attempting to replace the motherboard in my LED tail light. I realized that the only way to do this is to crack the seal and take the lens off. From what I have been told, the lens is PermaSeal'd.

Question:

1. Can I remove the lens with a heat gun safely?

2. When I reinstall the lens, what kind of weatherproof adhesive should I use? Will a silicone adhesive work? (such as this: http://www.amazon.com/Henkel-908570-.../dp/B0002BBX3U however, it is not recommended for plastics. I do like this: http://www.amazon.com/3M-08061-Plast...e/dp/B0002MID2 but it mentions nothing of being weather-proof. But it says it's for tail light lenses, so it has to be, right?)

3. Has anyone ever taken a lens apart and put it back together safely? I'd imagine the adhesive is not much different than the adhesive on my headlight lens.

Once I get some good information, will have pictures so others can figure see how to do it