Simulating low bandwidth network on localhost

[qvx]

I would like to test my CherryPy application in varying network
conditions, ranging from localhost full speed to low badwidth (ie.
14.4kbps) and variable latency from milliseconds range to seconds
range.

How can I simulate this? Are there some tricks to be played with Python
or is there a specialized software for this kind of things (preferably
free).

Thanks,
qvx