There are 4 extra bolts used on the E46 m3, and the z4m shares the same engine under tray. The extra bolts go into the lollipop bushes and front control arm rear ball joint (the one that attaches to the front cross member).
You'll need to use the E46 m3 lollipop bushes (which are not Eccentric) as they are only compatible with the m3 control arms.
Not sure what geometry changes would ensue but it's definitely possible. Only one way to find out I guess :wink: