USA Today Web site archives... By Edna Gundersen 'X'tra something out there on CD There's more to Songs in the Key of X than meets the ears. But X doesn't mark the spot, so good luck finding it. The hip all-star soundtrack, inspired by Fox's paranormal X-Files series, contains two hidden tunes by Nick Cave and Australia's trendy Dirty Three. CD bonus tracks usually crop up a few minutes after the last listed song. The less obvious X extras are tucked into the unnamable netherworld preceding the first listed song. "Everyone stumbles across a bonus track at the end of a disc," says Pete Howard, editor of the CD newsletter Ice. "But if it's hidden at the beginning, you have to know it's there. It's a fun way to give the listener something that may not fit thematically with the rest of the album." X-actly, says Warner Bros. vice president Geoffrey Weiss, who enlisted such X-Files fans as Foo Fighters and Elvis Costello to contribute original material. He describes Cave's songs as "incredible, really long and out of step with the rest of the record. Hiding them fits the X-Files idea that there are things we don't know." Cave and Dirty Three interpret the X-Files Theme (also done on Key of X by Mark Snow and P.M. Dawn) and a creepy violin-driven narrative, Time Jesum Transeuntum Et Non Riverentum. The Latin title means "Dread the passage of Jesus, for he will not return," a message scrawled by captive demons in Cave's eerie tale. To get there, go to track No. 1, press reverse and travel backward through the songs until the speedy din stops. Some CD players, particularly car models, won't cooperate. "It's an amazing thing to hear, and maybe this is the best way to hear it," says Weiss. "It's very X-Files." By Edna Gundersen, USA TODAY