Your best bet is to get into an electronics school and go from there. Also, the FCC has certain levels of certification for repair of transmitting equipment. I think the GROL is still in use. Many that they use to require are no longer required. Connecticut implented or "came to light" some sort of electronics/electrical certification, even if you are installing in vehicles. Apparently even the install guys at Whelen had to do this. They was a very big stink about it.
There is much more to radio's than "programming" them up. The vast majority is actual board level repair (becoming less and less at the field level), site installs, vehicle installs, PM work, trouble shooting. Its not all ways plugging in a couple and clicking ok. There is A LOT to know and to UNDERSTAND.
Programming a radio is about 1% of their work load. Once you setup one radio in the software, you just clone the rest and takes a min a radio.
In addition, the hours and pressure usually sucks, and not too many people are that happy with the jobs. Not to discourge you, but the industry is not what it once was 10-15 years ago with all the mergers on the radio shop wars.