I'm an MSII and I work (prn) as an EKG/tele tech. Prob will depend on the willingness of the hospital to hire and 'train' someone who will only stick around for a year or so.
If you go to a med school that does a lot of research, I'm sure you could earn a fair amount of dough as a guinea pig for the various projects -- you know, a sleep study here, a cardiac study there ... It adds up.
Certainly not all year long. I'm not exagerating when I tell you I'm working 13 hours every day right now, 6 days a week plus call days. You couldn't possibly expect to hold a job on top of that.