01 impala questions?

Hi, i've been doing my research on this vehicle and am a little confused. Some forums mention the need to power up the brown acc wire as acc or the engine will not crank. is this true? also some wiring says to get the parklight off the switch and others say to go to the bcm and use  a relay to avoid ses light from coming on.could some one whohas installed  on of these units give me some hands on advice please..Its an o1 model with passlock 2 ,no factory alarm It also seems like  you can remove part of the undercarriage and unplug the main ign leads and pull them down enough to wire  to 

Thanks Bruce...