I have found an employment advertisement asking for general interest for positions with a Hospital in 2012. The positions include Admin, Sterilisation assistants, Food Service assistants and Housekeepers.

I would like to submit my interest but would love some help in writing the cover letter. I have the admin background but would actually also be interested in the Sterilisation positions. As I'm returning to work and am finding it hard to get a job at all I would really not mind working in any of the above positions... but how do I formulate my cover letter to say that I would like to be considered for any of the positions without coming across as unsure of what I want or to not care one way or the other iykwim? Do I mention my background in admin and also say that as I have a long-term goal of working within the medical field (study midwifery) I would also be interested in the Sterilisation positions???
Or something along those lines??

Sorry to sound clueless but I really want to secure one of these positions as it is a hospital close to home and I've been hoping to work within a hospital setting for a while now.

I really want to write a winning cover letter and would appreciate any help offered!!

TIA