One ip. one file, one download at time - how?

hello, i would like to limit transfer on my server: one ip for one file
at the time. how i can do this? thanks!

limit_zone one $binary_remote_addr 10m;
limit_conn one 7;

in http section

On Mon, 09 Feb 2009 14:55:17 +0200, Joao S. [email protected]