nah, it works, you just have to make a tiiiiiiiiiiiiiiiiiiiiiiiiiiny custom shaped image for the pattern. like .125 square of an inch at the biggest.
oh wait, i know what youre saying. yeah, i havent figured that one out yet either. this is kinda of the poor mans way, it breaks up the pattern. but its kinda of the same effect.
you could always create the halftone, then layer your "S" sized appropriately over each dot.. LOLOMG
yeah, no i don't know, i'm sorry.
Go to adobe.com and search for custom dot pattern. Lots of different ideas there (Good News), but it seems you need to be intelligent and patient (Bad News).