Hi lumination, my friend says that voluntary work is the way to go at rescues etc. Do what you're asked quickly, cheerfully, without complaint. Become friendly with an inspector and let everyone know that you want to become. My friend says he had two interviews before he got the job (he covered a HUGE area) as an internal candidate beat him to the post. As I said the money is rubbish and the job is long hours and not easy. Some of the things you have to deal with can break your heart but you have to be sensible and not let sentimentality get in the way. And you'll want to commit murder many many times with some of the people you have to deal with.
So if you're serious, get down to your local rescue and get volunteering. Good Luck.