With Lorenzen the idea was to just use him normally as a reliever until he got enough PAs to qualify as a hitter. It pretty much meant he had to sign with a bad team that could afford to give him those 60 PAs. And then he would have had more trade value.
But correct, if you're currently a hitter, there's really no way to change your designation. But if you were willing to let someone get their 20 innings as a starter they would just be on your roster as a pitcher. Because there's no rule against letting your pitchers play the field or take ABs. As a reliever it would just take a lot longer.
And they'd have to be good enough.
