my brother had to pass a hydration test not too long ago for wrestling @ his school and he kept failing (they had him cutting weight), finally he took a visine bottle filled it with piss and diluted it with water... worked like a charm (in your case i guess you would have to find someone you trust to give you their "clean" pee.) also, my roommate had to pass a test where he works (and he smokes a LOT of herbal) he went to GNC and got a megaflush (i think thats what its called) followed the instructions, and passed.
::edit:: i think it was this stuff,
http://www.gnc.com/product/index.jsp...entPage=family