The Inspector should support the Firebug Command Line API (http://getfirebug.com/commandline.html).
<rdar://problem/5712816>
I agree, this is would be very useful.
A few of these are not yet implemented; please file bugs with links to the API docs if they are still wanted.
Created attachment 250418 [details] Patch
Comment on attachment 250418 [details] Patch Wrong bug.
Sorry, I inputed the wrong patch numer.