The starting URL can be set using the default referer:
 %R  default referer field sent in HTTP headers (--referer 
<param>)

That is, putting 
--referer <http://www.example.com/>
among with URls

> yep, all filter rules are used, in their order. last 
rule "overwrites" the earlier, if both fit to an object..

The last rule is prioritary ; that is, if is matches, it is 
the one taken in account.

Example
-* +www.example.com/*

Will exclude everything BUT files on www.example.com