iCal sharing

I have an iphone 4 , my wife has an iphone 4s, an my home computer is an imac. I am running 10.7.3 on the imac and ios5 on the phones. I am sharing my ical with all the devices. My question is, I would like to use my calendar alerts on my iphone 4 to alert me and only my phone but still show my calendars on my wifes iphone 4s with out having my alerts sound off on her phone as well as if she would like to youse her alerts on her phone, they do not come over to my phone all the while sharing our calendars so we know each others schedule. Is this possible?? If so, how can I acheive this?