I’d like this too, a lot… But haven’t found a workaround.
This actually brings up a bigger problem — in Final Cut 7 you don’t need the media in the Browser in order for a sequence to link to a clip. In Premiere, the clip (for some reason) has to be present in the Browser. It’s a completely unnecessary feature that actually makes it pretty difficult to manage projects… mostly in a program that doesn’t allow you to open up multiple projects at a time.