Is it possible for a cs undergrad like me to apply for a cs grad program and study computational biology?
I suggest that you make contact with the admissions of the target faculty, as well as make contact with academics whose research interests match the field you are interested in.  Have a look at the academic's profile pages as well as looking at papers that they may have published.

As JeffE said in his comment - why not?  You have computational background and a clear interest.