You need to enable CC in the ECU which requires an official scantool or a laptop with a mini VCI cable plus some obscure software drivers and ETACS decoder or MMcodingwriter, then you can either backpin into the connector with a DAOX switch (or make your own) that goes to the clockspring or try your luck installing a factory switch to the steering wheel, there's two different versions that have different resistance values, getting the wrong one will cause trouble, also make sure that the connector that plugs into the switch actually does something before buying a switch, in my case my green plug that went into the switch didn't do anything, so I used the former method. Also check your brake light sensor plug is suitable.
Hardness depends on your familiarity with all of the above and your patience.
https://mirageforum.com/forum/showth...bling-in-ETACs