ccord EX Radio w/ cd (Big Unit)

Hello. I was wondering if anyone tried to install this particular radio into another make/model (like a nissan maxima?). If you have, what did you do for the security feature? There is a wire marked security, and I'm not sure if there is going to be a problem or not. In case someone is wondering, it would be going into a 91. Any advise/information would be greatly appreciated! Thanks!!
Scott