I just embarked on this myself last month after my first track day where my brakes slowly started getting close to the floor lap after lap...should have done this before heading to the track!
The procedure is actually pretty easy with the right tools. I installed speed bleeders (from Pelican parts), used a Motive pressure filler, and the motive catch bottles. I only needed 1 liter of fluid to change the whole system.
I followed these directions:
Porsche Boxster Brake Bleeding - 986 / 987 (1997-08) - Pelican Parts Technical Article
It takes longer to get the car lifted up on jack stands and the wheels removed than doing the fluid change.