You can get into their CS program but you need to take some required classes and do well in them. Here is the link for changing your major and what are the requirements: http://www.changeofmajor.uci.edu/CoM_ICS.html
Like stated in the email, all majors are competitive, so if you meet the requirements you should be able to change IF THEIR IS ROOM. I would go for the direct admit at USD unless there is a huge difference in cost. Good Luck.