Unfortunately, I am in the same boat for my new car. I have not had any luck with this....I am trying to look into getting an alarm installed at the same time...if I figure it out, I will post it on here.
If you have just power locks but no key less alarm, that can be easily done. Just make sure you are going to a reputable stereo/alarm shop. But if you have no power locks, you will have to get actuators with the alarm.
I just had the Viper 211HV installed at Best Buy for $139, no alarm but the factory keyless isn't either. It has an AUX channel for accesories so I also bought the DEI 522t trunk release actuator off ebay and I am going to install that myself.
Sorry to dig up an old thread. I have a 2011 iSport with the power door locks. The car already should have the receiver for the standard keyless fob, mine did, however if you want to add the switch blade key it does need to be changed. When I get off work I'll post the instruction for the BCM responce so you can test to see if it's there. The ones for the 2011 are slightly different than what was floating around on here last time I checked.
I purchased the Viper Keyless Entry System and had it installed at Best Buy. $150 included installation. Works well and even comes with a small blue LED light in the car. Installation took about 4 hours but I dropped my car off and he called me when he was done with it.