well I doubt Z4 has an assembly that is very different.
I would consult RealOEM for parts and see where the clutch pedal assembly in 128i is also found.
128i:
http://www.realoem.com/bmw/showparts...91&hg=35&fg=05
same clutch pedal part #:
http://www.realoem.com/bmw/partxref....eur=&details=1
Seems e90 is the best match. Maybe they have it on their forum as a DIY..
I would love to see the DIY since I did consider the Derlin bushings 2 month ago. Also I don't know how many you need, 1 or 2 of the bushings