John Marcum and Kim Oppalfens have put together a great article from a collaboration that they took part in, to try and deploy FCS updates in a shared WSUS environment.
These guys look like they have cracked the problem and offer up the solution .. great work guys!
Read the full article here
Read the complete post at http://wmug.co.uk/blogs/r0b/archive/2010/09/27/fcs-updates-in-a-shared-wsus-environment.aspx