http://hints.macworld.com/article.php?story=20110322011218363
To double the size of the entire application, quit Quicksilver and run this:
defaults write com.blacktree.quicksilver AppleDisplayScaleFactor 2
It didn’t work well with my usual interface (BezelHUD), but for something like Primer, it worked surprisingly well and the text looks great at double-size. Unfortunately, the menu bar icon (if you have it) is also doubled, which looks awful.
To revert to normal, quit Quicksilver and run this:
defaults delete com.blacktree.quicksilver AppleDisplayScaleFactor
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Rob McBroom
<http://www.skurfer.com/>