I got this trick from a forum member called mediumsoftworks
He didn't post it in the Tips section but I think it deserves a place here
When you find a really good source on K-Lite (with good files and/or good speed) and you want to add it to your "Favorites" this is what you can do:
Just start a download from the source that you like and put it on pause. The next time you want to download something from this user just right-click to "Find more of the same user". If you use a download accelerator, make sure it skips paused items.