Re: How do you? mysite.com/customname ?
And you might be interested in the Apache rewrite rules... See http://doc.tikiwiki.org/Documentation and search for rewrite rules...
And ask, if needed, on mod_rewrite forums on the web for help, if you can't go further in tw forums... (most of us are not expert on mod_rewrite...)
HTH
P.d. By the way, Welcome to Tikiwiki Community! 
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