Replacing search query strings to make it SEF
You can use this rule:
RewriteCond %{QUERY_STRING} ^(searchword=[^&]+)$ [NC]RewriteRule ^ /?%1&Search=&searchphrase=all&limit=50&ordering=newest&view=search&option=com_search [L,NE]
The best way to do this is by adding a router.php file to your component. Take a look at http://docs.joomla.org/Supporting_SEF_URLs_in_your_component