Just put Eibach lowering springs on my 155, the rears are easy but the fronts are a different proposition.
There is a nut on top of the strut which needs to come off while holding the bolt with an allen key. You cannot undo it with only a socket as the damper will just turn. Couldn't do mine and had to take it down to a local garage with an airgun to undo the nut.
Apart from that its all a bolt on bolt off job! You will need some good spring compressors.
The rear caliper piston needs to be wound back (turned clockwise whilst applying pressure) not just pushed in or the ABS will be damaged...........thats for the 155!!! Don't know about the 146 or other Alfa's.