Aftermarket Mp3 Player

I pulled my mp3 player out of my 94 chevy blazer s10 before I traded it in and got my alero 2 weeks back. Do any of you know if that wiring chasis will lineup correctly with the alero wiring setup. Both GM and 94+ so am just wondering. I also want to know in my 02 alero there is a security light on my current CD player unit that is stock. What exactly is that. Does it just prevent it from going into other dash units, or will it prevent me from having an operational mp3 player unit in my alero without taking it to an installer which would have to do something special to the unit after/during removal. I have had the dashboard completely disassembled around the player (the plastic around the climate controls and player as well as the shifter) and there is a starbit screw along with 4 mounted screws at each corner of the player. Do I just remove the starbit and the 4 screws from the unit and it should come right out, and is the starbit there for any particular reason because my mp3 player does not have the screw hole for that starbit. What should I do after removing it if it has to be mounted? Please help.

THANKS!