You can definitely take one of the courses in the summer, or as lorend mentioned above, you can push these electives to your second year. (You are allowed to take 48 units of level 1 courses (16 half-year courses) before you graduate...for most people this isn't a problem)
I just thought it was worth nothing, that a potential problem with taking courses in the summer is that they simply may not be offered. In my experience however, the courses offered in summer school don't vary a whole lot from year to year (particularly the first year choices), so maybe take a look at this year's summer school course timetable (found here:
https://adweb.cis.mcmaster.ca /mtt/).
Just change "session" to SPRING/SUMMER 2009, and search by Department (Music, etc.)
But the point is, if you don't see any of the three courses you'd like to take on there, they probably won't be offered next year either...at which point you'd have to push them to 2nd year.