Sorry to say but it can't be done . They are totally different types of refills . Also most Rollerball refills have to be capped or they will dry out , even the capless refills will only last about a year uncapped .
You could use a parker style Gel refill . They write almost as smooth as a Rollerball . Skiprat did a parker slimline a couple of years ago , he used a reversed a slim tranny somehow . With any luck he will chime in with some ideas .