I have created a search plugin for Firefox that will work with RCDB to get it, go here: http://www.filesavr.com/rcdb
This does work, I have tested it. The only thing wrong with it is that I can't get the right logo to appear on this, so right now it's a generic logo. If someone can get the RCDB logo on there, go ahead and modify this plugin and let me know. I'll give you credit wherever else I post it.
To install:
1. Download the file here: http://www.filesavr.com/rcdb
2. Find your Firefox profile on your computer. It should be in a directory similar to this:
C:\Documents and Settings\<user name>\Application Data\Mozilla\Firefox\Profiles\
**Note that the Application Data folder is hidden and you won't find it unless you change the view settings Windows Explorer.
To view hidden folders:
1. On the menu bar (under the title bar) go to Tools and select Folder Options.
2. Click on the View tab and in the Advanced Settings area, find Hidden Files and Folders. Check "Show Hidden Files and Folders"
3. Your Firefox profile name will be a string of random numbers and letters. Select the one you have been using (likely the default, and there should be another name appended to it to mark it otherwise).
4. Open the searchplugins folder and copy the file you just downloaded (rcdb.xml) into there.
5. Restart Firefox and this should work.