If all you want to do is to fly at work then it's all taken care of by company simulator checks and the paper work is all done by the trainer and filed or retained by the company. If you want fly outside of work you need to meet the same requirements for each group of aircraft (SEP, MEP etc) as anyone else. The IR is also now type specific so it's only valid on the aircraft that you do your sim. check on, if you want to fly a light aircraft you need to renew your IR in that aircraft type or group as well.