I got this code, and that works well:
<customer_account translate="label"> <reference name="customer_account_navigation"> <action method="addLink"><name>someName</name><path>somePath</path><label>Some Label</label></action> </reference> </customer_account>
But I just want to add this customer account navigation link for specific customers. I would be able to write some PHP what acquires the information if the user should view the custom navigation link, but i cannot do this with XML.
What is the solution for this problem?