Scope of practice is regulated at the state level. You will need to check with your state practice acts. It is also likely to be different, depending on whether it is happening in an outpt or inpt setting.
If it is permitted by your state, you will need to provide training and competency validation in EXACTLY the same way that it is provided for nursing staff. Otherwise, you may be vulnerable to accusations of not providing the same standard of care. This is a huge no-no for regulatory agencies.
Our rad tech do it all the time. You don't have to have an official certification from the state (or anything). The facility just allows it if you get the proper on the job training. It just a phlebotomy class or IV insertion class and then you get checked off for starting so many number of IV's. Maybe a computer training course on top of that. And, you don't have to be deemed an expert to start IV's.
In my department CT, MRI and NM technologists start IVs every day. We also access power injectable PICC and ports for contrast injection. We start IVs on outpatients and inpatients who don't already have an IV when they come to us.