@The Mighty Atom
It's a very old map hack from Quake days, and it's not worth your time. All you have to do is make a simple brush in Worldcraft, save it as a .MAP file, and edit the output with Notepad. Here's the map file format from Valve Developer Community:
(x1 y1 z1) (x2 y2 z2) (x3 y3 z3) TEXTURE_NAME [ tx1 ty1 tz1 (shift x)] [tx2 ty2 tz2 (shift y)] rotation scalex scaley
Here's my five second attempt. It's a simple, flat face (this is before the edit):
( 0 0 -32 ) ( -64 0 0 ) ( -64 0 64 ) CRATE25 [ 1 0 0 0 ] [ 0 0 -1 0 ] 0 1 1
Bam!
( 0 0 -32 ) ( -64 0 0 ) ( -64 0 64 ) CRATE25 [ 0.8 -0.75 0 0 ] [ 0.4 0.5 0.75 -32 ] 0 0.80 0.80