Yeah that is handy. I have it set up that way in my admincp.

It does require a single file edit.
In admincp/index.php find:
Code:
construct_nav_option($vbphrase['search_in_templates'], 'template.php?do=search', '<br />');
Below it add:
Code:
construct_nav_option($vbphrase['edittplates'], 'template.php?s=&do=modify&expandset=3&group=all', '<br />');
In the code above where it says &expandset=3 you'll need to change that number to the template set # you want to edit by default. Also, I think "edittplates" is a standard phrase but I can't remember.. So you might have to add that phrase.
Dewayne