there are
several ways to get the streaming address
i use developer tools in chrome to browse the resources of the page
you can search for mms, asx or rtmp depending on the stream type
for pages where you cannot find the stream you can use
URL Snooper or
Replay Media Catcher.
once you have the stream try playing it in vlc via open network.
if it plays there it will play in xbmc so save the url of the stream as a .strm file with notepad
if theres some particular sites you are trying to get working post the site and I will tell you how i found the stream and the format it needs to be in for xbmc