I've seen some tools on Alibaba that can be used to open the housings. I'm sure that you can find the equivalent of them in a hardware store. They look like some sort of midevil torture device that you can stick the headlights and slowly "crank" open...let me do some digging.
EDIT: here's the tool I saw.
http://www.alibaba.com/product-gs/53...fit_tools.html his price is way, way too high, it looks like a trim removal tool to me. i'm not sure what it's called though, but head down to your local awesome indy shop and show them the add for the tool and ask them if they know what it's called! If I find out, I'll update this. I imagine you could break the seal with this, and use Popsicle sticks to keep the headlight open.
And an E92 Pre-LCI isn't permasealed like the E90 Pre LCi and E90 LCI. So we have it much, much more difficult.