Right, so here's the start of the next update. My apologies for the picture quality, I haven't got access to the D90.
It was getting quite overcast outside, and I can hear thunder in the distance, so I decided to bring the washing in, and wait until tomorrow to spray the case. However, it did allow me to prepare the case parts, now that they're all covered in finger prints and metal shavings.
I've basically used the same technique I used to use when I sprayed RC car bodyshells, as it works well.
So, here are the parts after removal, and the various cutting/dremelling etc. The dust and finger prints are easy to see.
Always listen to something decent in the background 
Note Lian Li's helpful QC sticker remnants
First, wash the parts in hot soapy water. I don't find that using a cloth works any better than hands at this stage, so I just use my hands to wipe the surfaces.
I know my watch is black, but I'm not a goth...
Secondly, rinse the parts with cold water to remove any soap suds, as they will dry with a nice film that prevents the paint from sticking.
Then dry the parts with a rough tea towel, this 'roughens' the aluminium very slightly, and helps the paint to stick. After that, you are left with some lovely clean, finger-print and grease free parts ready for spraying. Obviously avoid handling the bits except on the edges right now - basically like handling a motherboard.
Lovely Lian Li aluminium goodness
Hopefully the body-shell spraying technique will work quite well overall, if not, call this 'guide' a log of how not to do it...
. I've never painted anything before (usually outsource) but quite fancy doing some spray-painting of some old cases.
