As for disassembling, You may find those 2 videos helpful:

http://www.youtube.com/watch?v=aVEHm325-z8 <-- This one is very good, but they don't "tear" it down to smallest possible parts. they stop @ around 3/4.

http://www.youtube.com/watch?v=RYIn3q6av18

This one tear it down completely, but it is set of pictures, not video. Also, they write some bullsh*it about not using screws again etc - ignore that, just focus on disassembling parts.

Overall, disassembling N900 is very straightforward process - much easier, than one might expect. The most tricky part, IMO, is to remove camera module - at least, if You don't have specially crafted tool (I don't have it also). You need to mimic it's usage, by use of other small tools. It may be worth to do, though, cause I think such a heat may seriously damage camera's optics/sensor.

Good luck, I'm holding my thumbs!