How to restrict peer bandwidth use

[ariel at fismat.umich.mx]

Hello:

Is there any way to restrict the bandwidth used by every wireless client.
I have many users, and i need some to have only 56Kpbs, others 1Mb and
others should have full bandwidth.

Merely i just need to restrict internet access, if they can have
11mbps(with luck) between themselves would be great, i only want they to
have slower connections to the internet.