Patch
svn co -r 28276 http://xbmc.svn.sourceforge.net/svnroot/xbmc/trunk xbmc-trunk-r28276
wget http://xbmc-boxee-iview.googlecode.com/svn/trunk/xbmc/swf_patch/rtmp_swf_verification_svn28341.patch
cd xbmc-trunk-r28276
patch -p1 < ../rtmp_swf_verification_svn28341.patch
Then compile XBMC as you normally would, with ./bootstrap, ./configure, make, sudo make install.
FIXME: Patch needs to be fully tested. Initial testing works with ABC iView and BBC iPlayer, but RTMP Urls need to be changed.