Here in the US, beige boxes work...and though I've never heard of this 'scarlet box", it sounds like it could work *shrug*
Unfortunately, the favorite phreaking tool of the US, the Red Box, has become harder to construct as time has passed, and phone booths have become harder to fool...to the point where you have to physically rewire the actual booths sometimes.
I'll poke around some BBS's and IRC rooms, and see if I can find any info for ya, pak
-Grim