Here's a quick write-up from my 535i H&R Spring install. This is from memory so I'm sure I'm missing a few steps. Sorry I don't recall the socket and wrench sizes. Please use these photos for reference only and it is by no means a complete write-up.
Before pic
Front suspension
Remove sway bar link and move it out of the way
Remove lower shock bolt
Remove strut mount nuts
Remove strut by pressing down on the aluminum arm and maneuver the strut out of the control arm. You'll need a buddy for this step. This step was a bit challenging but it is possible to remove the strut without removing any additional components.
Here's the stock front strut
Swap springs by using spring compressor to compress spring. Swap spring out with H&R. Sorry no pics of this step.
Rear Suspension
Access rear shock mount nuts by removing rear speaker grills and speakers. You'll need a stubby swivel socket wrench and a torx bit.
Remove shock mount nuts
Remove lower shock mount bolt
You'll notice that the shock won't come out since many components are blocking it's way out. I found that if you remove the following components, you'll be able to remove the shock:
Swap over H&R Springs
Comparison of stock spring to H&R spring
Button everything up to Bentley torque specs and let the suspension settle for a few weeks before aligning. Will post after pics shortly. Good luck!!!
Also, if you are in so-cal and are too lazy to do the spring install yourself. PM me and I'll refer you to my buddy who helped me with the install. We knocked this out in about 3 hours.