newbie Question about PKCS#7

I'm very new to the topic of XML Signature and I have therefore a rather simple question, which I couldn' solve myself by reading the spec. I wanted to look, if this topic was already discussed in your list, but the mailing-list archiev was down. 
What I want to know is: How can I include the PKCS#7 Standard in an XML Signature? Do I have to use the http://www.w3.org/2000/09/xmldsig#rsa-sha1 URI? 
 
wbr,
Roman Huditsch