Honestly speaking to say I don't think you will get CSE in IEM.I have seen IEM’s CSE Closing rank is within 2100(After 3rd round counselling) in WBJEE(I am talking about 2016 and 2017).But you will surely get IT.If you inclined towards Computer Science releated staff, then I strongly suggest you to join IT in IEM.Basically in placement IT students get equal opportunity like CSE students. It's just that CSE students get more offers than IT students.

Also if you will maintain decent cgpa in 1st year(Above 8.6), then you have option to change your branch into CSE in 2nd year. I strongly suggest you to join IEM.It’s a good college for CSE/IT.