Apologies for such a late reply on this, but I’m gradually catching up on some posts I see have not been answered.
You need to install ‘gnome-devel’ as a tgz file. That’ll give you gnome-config.
– Thomas Adam
As an aside, I think gnome-config is part of Gnome 1.4 (gnome libs more precisely) as it’s got this ancient version nunber on my system (1.4.2)
That’s right – gnome2 did away with it in favour of something else that doesn’t work. 
So much for writing from scratch. 
– Thomas Adam