$request = $smcFunc['db_insert']('replace',
'{db_prefix}package_servers',
array(
'name' => 'string',
'url' => 'string',
),
array(
'Gamerz Garage', 'http://www.gamerzgarage.com/mods',
),
array( 'id_server')
);
That should do it.
It will replace the entry if it exists otherwise it will insert it.