PHX fire runs rescues (unlike most of the other valley FDs) but you need to be a full fledged PHX firefighter to staff one so unless you're planning on going through the whole process of getting hired on it's not a viable option.
Try dropping an application with Southwest and with PMT. Yes, they're both owned by Rural/Metro but right now they're still essentially operating as separate companies - HR included. SW is about to create a whole bunch of part time positions (no idea why, probably to limit full timers available OT) so maybe you could get in on that at least.
If you want to stay in Mesa and are considering ER tech positions (not sure exactly where you are) you should check out Banner Desert, Banner Gateway, Banner Baywood, Arizona Regional and if you don't mind going a little farther east, check out Mountain Vista.
Additionally you could look into EMT positions at local casinos, I know a lot of people who got their start that way.
Also, there's First Responders PHX, but they only do stand-by. Still, they hire EMTs AND you'd get to watch a lot of d-backs baseball in the near future. No idea if they hire full time though.
Hope that helps.