The flush process on bikes with "whizzy" brakes is complicated because there are separate wheel and control circuits that need to be flushed. The reservoir on the handlebar, for example, does NOT directly connect to the front calipers. Some, not realizing that, have sucked the reservoirs located in the ABS unit dry while wondering why the fluid in the reservoir never drops.
Read this doc ==> http://users.rcn.com/dehager/service/service_abs3.pdf
to understand the brake flush procedure needed for your bike.
I work slow. I allocated about 4 hours to flush brakes on my '05. I did that every other year.
It's not a difficult process. Just tedious to get the Tupperware and tank off and back on again. I did it just shy of two years ago, and it took maybe four hours including replacing the front shock while I had the tank off.
I did the job, just the brake flush this time, last Friday. Took a bit under two hours.
A few notes that make life a bit easier:
1) you really don't need the precision-fabricated wood blocks; you just need to fully retract the caliper pistons. Many people do this by shoving wooden wedges (standard hardware store shims) between the brake pads and rotors, or removing the calipers sufficiently to just fill the space between brake pads with shims. This is the way I did it when I found the blocks I'd carefully made were the wrong thickness...
2) you no longer have to do four separate bleeds on each control circuit. According to ADVrider, BMW released an updated procedure in 2006 (I believe) that requires bleeding only one fitting per control circuit. I've attached the photo from the ADVrider posting.
3) if you don't have a set of box-end bleeder wrenches, go out and buy some. Six point, 7mm (for the module) and 8mm (for the calipers). Cheap 12-point wrenches can round fittings and wreck your day.
4) the change consumes more fluid than you'd expect--buy a full liter, you'll probably use it all.
5) one more thing: while you don't strictly need the special funnel that threads into the module to fill the wheel circuits (you can make your own by wrapping tape around an ordinary funnel), I have found the one that Beemer Boneyard sells to be well worth the $35 investment.