keyless entry installation

i have a 95 grand prix 3.1 se
My car doesnt have keyless entry and i would like to add it to my car. I was wondering how hard one would be to install. Does anyone have any tips or guides on where and what to tap into for wiring?? I am pretty good with wiring up things, but i havent attempted a keyless entry installation before. I was thinking about this one: http://www.etronics.com/product.asp?stk_code=pylpwd511&store=&catid=297

Product Manual: http://www.pyleaudio.com/manuals/PWD103.pdf

Thanks in advance!