Let us review the typical duties of a trainee: faxing, photocopying, fetching. But Jared Poe -- a 22-year-old UCLA grad paying his dues in the writers' offices of ''The X-Files'' -- added one other task to his list: kickin' it on screen with Scully (Gillian Anderson) and Doggett (Robert Patrick). Owning no professional acting credits, Poe boldly asked ''Files'' exec producer Frank Spotnitz if he could audition for a meaty guest spot in the May 5 episode as a mysteriously brilliant FBI cadet with unusual insight into the unsolved murder of Doggett's son. ''I honestly didn't expect for a second that Jared was going to get the part,'' says Spotnitz, ''because it's a huge part and I'd never even seen him act.'' Lo and behold, Poe went through the casting process and beat out about 30 others. ''He was the best,'' adds Spotnitz. ''He won it fair and square. I mean, he was as surprised as we were that he got the part.'' While he's grateful for this big break, Poe says he's also focusing on becoming a writer-director. ''Hopefully something will open up,'' he notes. ''And if not, I could always just go back to filing.''