Change XBMC User Agent

Hi there,
Sorry if this is the wrong place to ask about this. I could not find a proper answer on the forum.

Is there any way we can change the user-agent of xbmc? Or is this plugin-specific?

Some say that you have to change the sourcecode and complie a new version of xbmc, while some say you can add |User-Agent="string" at the end of a video stream to override the useragent.

I've tried the latest. Without the tag the stream stops straight away (log file).
But with the tag, i can see that it loads stream type, bitrate, codecs, etc, and then it stops.

Is there a way we can do this?

Thanks in advance