People who have never bled ABS brakes often ask what the correct procedure is for bleeding brakes. The 100% BMW way to do it is to take your bike to the dealer and have them hook your bike up to the BMW computer. This allows the maintenance technician to modulate the ABS during the bleeding process to make sure that the very small amount of brake fluid in the modulator gets refreshed.
At $95/hour for labor with additional charges for taxes and brake fluid that gets rather expensive. Though not the BMW proscribed procedure, I do my own brake bleeding as described herein and have never had brake issues.
The procedure for bleeding brakes it to first bleed them at the ABS modulator and then at the caliper(s). I usually use a MightyVac vacuum pump but I have also used the normal manual approach where you repeatedly open the bleed valve, s-l-o-w-l-y apply the brake, close the bleed valve and then release the brake until you've flushed the system.
If you're using the manual approach many people recommend not having the brake lever/pedal travel more than half way as there may be something in there that will get stuck in the seals and cause the master cylinder to leak. I've never had an issue like this happen to me but if you want to err on the safe side I don't think it hurts. It will just take you a little longer to bleed the brakes.
In order to deal with the issue of the brake fluid in the modulator I take the following approach. Before bleeding the brakes I take the bike out and get the ABS to engage, one at a time, usually the rear first and then the front. If you've never had your ABS engage then it's a god idea to do this anyway so that you're familiar with what happens when the ABS engages in the real world. Try it while going straight in a nice level empty parking lot where it's safe. Do the rear brake first and take another run and get the front ABS to engage. I usually do each about three times before I bleed the brakes.
After I've bled the brakes, I take the bike out again and get the ABS modulators to engage a few more times. My theory (which may not be correct) is that this at least gets the old brake fluid in the modulator at least mixed up with the fresh fluid. It certainly doesn't hurt and practicing panic stops is a good idea anyhow.
Additional cautionary note: Do not overadjust the set screw on the rear brake pedal. Your best bet is to leave it where it is. The reason is that if the piston in the rear master cylinder is pushed in too far it can get stuck on the set screw that holds it in - resulting in a locked or partially locked rear brake. If this happens when you are riding PULL OVER IMMEDIATELY. On 4 valve paralever K bikes, the rubber boot on the front of the final drive is very close to the brake rotor. If you ride with a partially locked rear brake the rear rotor gets extremely hot and in a very short distance (less than a mile) it will get hot enough to light the rubber boot on fire. This fire is very hard to put out and can cause lots of damage - to the rotor, final drive, rear caliper and brake lines - possibly worse if you're unable to get it extinguished quickly.