Firefox: can a shortcut be defined for a site specific Google search?

"Yes, and the exact same syntax is used in the Firefox bookmarks. You may want to do a google search that you want with some replacement for the text you want to replace (I use XYZZY for this, it's easy to spot). Then replace XYZZY with %s, and add a ""keyword"" to the bookmark (it's in the ""more options"" section of the bookmark manager). Then you can type the keyword and whatever you put after the keyword will replace %s in the URL.

See this reference for keywords in Firefox. I tend to leave the trailing colon out of my keywords, they're easier to type. Lifehacker also had a decent article on it which may be more recent."