How to add search engines to Safari?

Hi,

Is this now possible to add my search engines of choice like Wikipedia or Google Images to Safari? I use Safari 5.5.1 on Lion. Maybe editing a plist file? Or is it still built in the executable like this 2007 discussion conclude? https://discussions.apple.com/thread/1214131

I mean without any extension like Glims, which offers too much for me.

Thank you!