Here's a way to add a search engine to the search toolbar in internet explorer:
(Notes: Do this with caution! Also you can only do this using the single search engine option; I'm on my way to find a way to do this for multiple search engines.)
1. Download this page: http://ie.search.msn.com/en/srchasst/srchcust.htm
2. Open this in your favorite text editor or html editor
3. Search for the line: <OPTION VALUE="http://www.yahoo.com/search/ie.html">Yahoo
4.Insert above it or anywhere you like this line (I'm adding google):
<OPTION VALUE="http://www.google.com/ie">Google
5. Save the file, and open it in IE.
6. Change the option to use single search engine
7. Find google on the list. If you're having trouble seeing it, try and click on any remnants of the scroll bars to find the list.
8. Open a new window, and then the search tab.
To reset it, just click customize in the search tab the usual way.
[Editor's note: I have not tried this myself, as I haven't used IE in quite a while...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020113124806503