Since version 3.8.10 LimeWire supports magnet links under linux. Here is how to download a magnet link:

1. Make sure Limewire is running and connected

1. In your browser, right-click on the link and select "Copy Link Location".

3. Switch to Limewire. It will ask you whether you want to download the magnet uri.

4. Press Yes and enjoy!

This works with mozilla/netscape/firefox and konqueror. If you use a different browser, the steps should be similar.