how to install?

a commencé à faire des pressions sur celui qui est actuellement au volant; a eu des visions cauchemardesques de l'airbag qui se déclenche. Toute information sur la façon d'installer correctement cette pièce de remplacement (ridiculement trop chère) sera appréciée. Merci d'avance.

Je crois qu'il y a des vis à l'arrière de la roue qui le maintiennent. Je ne crois pas que vous deviez enlever l'airbag, mais ça pourrait être une bonne idée.

Have not done it myself however this should be about the same as it relates to airbag and trim (9-10)
http://www.m3post.com/forums/showthread.php?t=242963

Also read this one
DIY: Removing steering wheel trim

You will have to remove the airbag first in order to remove it. Here is the best video I have found to make it easy.

The release holes referenced in the video are covered by the leather, therefore you'll have to use a something sharp in order to make a small hole as possible and then use a small screwdriver to release the airbag.

I just did this to my car yesterday. I did not need to remove the airbag, but it would've been a little easier if I did. You simply need a T20 Torx driver for the three screws that hold the trim from behind the wheel and the two that hold the buttons. If you don't remove the airbag, be prepared to wiggle and have less room to unscrew the buttons. The whole process took me 15-20 minutes.

How much does it cost & can u post the part#?
I need to this soon....thx

Pick the one you need:

http://www.ecstuning.com/BMW-E90-M3-S65_4.0L/Search/SiteSearch/Steering_Trim/

I put in this and the fit was perfect:

http://www.amazon.com/AutoTecknic-Carbon-Fiber-Steering-Wheel/dp/B003QACOWS

subbedddd im going this soon to replace me wheel with the perf wheel