The purpose of the ART program is to keep Reserve and National Guard units functioning outside regular drill weekends. ANG and ART Civilian Jobs require you to affiliate with National Guard or Reserve, that means you have to join the Guard or Reserve, or already have to be in the guard or reserve, to fly for them. If you are not already an Air Force pilot you will first have to be selected for UPT by the particular guard or reserve unit you are hoping to work for ,which means you have to meet all the requirements to become an Air Force pilot such as having to go OTS, not be too old etc. Once you complete UPT it will probably take several years before you would be considered for an ART position.
These jobs are really set up for guys coming off active duty as pilots, or experienced pilots already in the unit. Nearly every pilot in the guard or reserve probably has an application in and every few years a guy is brought on full time in an ART position, usually an experienced aircraft commander and instructor pilot.