Nope.
However, you can work around it. Make sure you have the status bar showing (View>Show Status Bar). Open a google.com
advanced search page*. Click in the Find results "with the
exact phrase" field. In the status bar, a magnifying glass with a + on it will appear. Click it to add the search shortcut. In the dropdown sheet that appears, change the keyword from google to something else if you don't want to replace the default google search (e.g. I picked poogle).
OK, whenever you want to search a phrase, either a) copy/paste the phrase to the search field in the toolbar and select Google Advanced Search from the drop down list (or leave it at that by default), or (b) highlight the text and press command-shift-F to auto-populate the search field, or (c) type poogle in the location field followed by your search phrase.
I've created a short movie of me doing this -
click here to view it (4MB)
*Note, if you want to display more than 10 hits per page, select the number from the list for this prior to creating the new search shortcut using the magnifying glass. This applies for any other parameters you might want to set at this stage.
Edit: By the time I had filmed it all, you'd worked it out for yourself anyway ;)
I'll leave it up for the benefit of people finding the thread at a later date.