> Is it possible to mirror only part of a site? For 
example, 
> I want to mirror <http://www.yoursite.com/sampledir>

+www.yoursite.com/sampledir*

> And exclude any pdf files and ignore exernal links.

-* +www.yoursite.com/sampledir* -*.pdf

(exclude everything, then accept files in 
www.yoursite.com/sampledir, then exclude pdf files)