Forums mIRC Help How to limit my download speed?

They have ways of doing it but its rather tedious.

One way is to do exactly what was stated, bandwidth limiter or bandwidth shaper. Traffic shaping is the idea that the client drops packets, the TCP will actually notice that its packets are being dropped, assuming its congestion it will slow itself down to try to avoid retransmiting the same packet over and over.

but there doesn't seem to be an easy way.

There is a way of doing it though, it would require that you intercept the DCC request with a proxy (scripted or compiled daemon/service) that would control the flow by buffering til the OS starts sending ACK packets back to the server saying to stop, and just reading a max of say 40kb of data from the buffer every second. The server would slow down because the nature of TCP is to not lose data, so it would slow down if its packets had to be retransmitted over and over again because they are being dropped (due to congestion is the main cause).