Quick way to enable only the web searches I want in Quicksilver
The latest Web Search plug-in from http://qsapp.com/plugins/ has newer lists that don’t rely on Blacktree. You should install it.

And if you don’t want to use the defaults (I don’t), just go into Preferences → Catalog → Plugins and uncheck them. No need to go digging into bundles and hacking at their property lists.

From there, you can add your own using the method if your choice. (Manually, bookmarks, OmniWeb search shortcuts, etc.)

Changes you make inside the plug-in’s bundle will be destroyed on every upgrade. Use the catalog preferences to ensure your search list stays around.