well, I can't claim to be the instigator of this deal, but I definitely participated. Used to hang around alot on M3Forum when I had and E46 M3 - just so happened that when I sold my M3 and got into the M coupe, they were doing this wheel build. One of the main guys at RAC has a Z4M and was the reason I was confident I could make them fit - they were made specifically to the E46 chassis.
http://m3forum.net/m3forum/showthread.php?t=301635
It's a looooong thread, but you can get the gist of the deal. I feel lucky.