1 - 2 hours
Just your standard Yellow Light of Death.
The whole process took about 2 hours, but, I stopped along the way to open up the power supply, and see if I could detect anything amiss. But, I eventually, with a few stops along the way, got it all back together. I was fairly familiar with the insides of these old-model PS3s, so I didn't have to refer to the guide much.
Make sure you have a rather large work-space. Like, 2' by 4' at least. Also, I'd recommend using something like an egg carton to hold screws, and place the screws in whatever order makes more intuitive sense to you, either by type of screw, or by step you were on when you removed them.