In case of non-boost theme this is what we do:
We find the first category in the Administration block (for example "Forum administraion"), get it's name and then execute step I navigate to "Edit settings" node in "Forum administration"
This is the code:
public function i_navigate_to_in_current_page_administration($nodetext) {
$parentnodes = array_map('trim', explode('>', $nodetext));
// Find the name of the first category of the administration block tree.
$xpath = '//div[contains(@class,\'block_settings\')]//div[@id=\'settingsnav\']/ul/li[1]/p[1]/span';
$node = $this->find('xpath', $xpath);
// Add the name of the first category of the administration block tree to the path.
array_unshift($parentnodes, $node->getText());
$lastnode = array_pop($parentnodes);
// Execute the step "I navigate to ... node in the ...".
$this->select_node_in_navigation($lastnode, $parentnodes);
}