I have to correct me:
wxWidgets is installe below /usr/lib64 in centos and in fedora14.
wx-config is a softlink to /usr/lib64/wx/config/gtk2-unicode-release-2.8 or /usr/lib/wx/config/gtk2-unicode-release-2.8 or any other configuration, so if you change the link, it should work without that hack.
On fedora it's a wrapper-script, that can be called with the --arch argument to force an arch, without the argument the result of uname -m is used.
Maybe update-alternatives exists for centos (as it does for fedora and debian/ubuntu), to configure /usr/bin/wx-config the "right" way (it does not exist or is not installed on my system).