Just wanted to post and say thank you Bailey! I successfully downgraded my launch 60gb fat PS3 using the guide.
Some things I noticed were that my COK-001 motherboard has a NAND chip on the other side of the board (backside) rather than both being on one side. This lead initially to some confusion on which was the Flash 0 (top) and which the Flash 1 (bottom). But after swapping them in FlowRebuilder (when merging the two and checking the files it created) allowed me to determine which was which.
The biggest pain by far of the whole process was getting that solderless clip on correctly for WinSkeet to recognise it. I would add that gently scrubbing the pins with some cleaning Alcohol on a clean toothbrush (on the solderless clip and NAND chips) can help in making sure it's won't fail due to the pins being dirty (as that was the case with my solderless clip).
Any way, thanks for making a coherent and easy to understand guide Bailey!
P.S. If anyone is still looking for a shop that sells ProgSkeet 1.1, [shop.01media.com] has them in stock. That's where I got everything I needed (ProgSkeet 1.1, NAND adapter PCB, 360-clip and Injectus programmer).