It's not hard to find creative writers online, but looking at resumes I'm not convinced they would be cut out for IF. Has anyone hired a creative writer for a project?
Provided they are story writers and well equiped for your particular genrie-fantasy, sci-fi, romance, etc., I do not see it being much different for IF or short stories/novels.
I am not sure how "professional" writers do it, but there are quite a few sites that have story writers and they have all their works up. You have to read their stories to see if they are good enough and agree with you though, but there is nothing to hide or pretend about, like saying anything in a resume or at a job interview.
Just don't fall for the highest rated ones are always the best. Although no doubt good, a lot of writers don't bother with trying to be famous and just write, so they do no get very well known in the community as some others.
There are a number of writer's groups on facebook, you could start there. Or if there's a writer's group local to you (books and short stories writers), join it and maybe you can find people there. Also, you might contact the local High School creative writing teacher - some of their students, or the teacher themselves might be an option. Or you could probably hire people here. What genre are you working with?
There is no difference between a short story or a book you read, and an IF you play. Other than the mechanics involved.