This shows basic use of SCALE OBJECT TEXTURE. The problem that Van B is describing is that in this example, 4 sides are now tiled correctly, but you now get two squashed textures on the ends. You have to make a special box object in a 3d package and uv map the texture. This is where you specify what bits of your texture cover which polygons.
sync on : sync rate 60
set text size 60
text 0,0,"F"
get image 1,0,0,64,64
make object box 1,20,10,10
texture object 1,1
scale object texture 1,2,1
position camera 0,40,-40
point camera 0,0,0
do
turn object left 1,1
sync
loop
Boo!