Just take the gravel vac and put it a little above the sand and swish it around. It'll stir the loose crap up and you can suck it up pretty easily. More easily than gravel because you can see where teh crap is and usually its all in the same spot.
The best way to clean the sand would be with a clean up crew, hermits, snails, star fish ect... they will go through and sift the sand preventing any of it from going completely anerobic and they will also eat the detris
Brahm
I just started doing a fishless cycle on a freshwater tank with sand. I am probably going to use a gravel vac like DannyJ88 said. I am also going to give it a stir every once in awhile. I would get some cleaners for the tank, but the tank is only for African Dwarf Frog's. I am actually hoping that they will be fairly clean.